[4]

Machining A Replacement Cross Slide For A Logan 11" (as Promised)

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#1
As promised, herewith are my experiences thus far machining a replacement cross-slide casting from Andy Lofquist at Metal Lathe Accessories to fit my Logan/Wards 11" lathe.

As I described in another thread, I want to replace the rather short cross-slide that came with the lathe originally. I want to replace it with a much longer one with tee-slots in the rear (so that I can use a rear-mounted toolpost, rear-mounted boring bar holder, etc., without necessarily removing the compound slide). Unfortunately, the drawings that Andy made are for a South Bend lathe which uses a different attachment mechanism for the compound slide.

As described in the previous thread, the trickiest thing to wrap my head around before getting started was how to mill the circular tee slot. Please see that thread for details.

This is just the first of likely several posts in this thread.

Here's a shot of the original cross-slide (with the guide nut installed):

IMG_0472.JPG
IMG_0471.JPG

The first thing I did was to mill the bottom of the casting to use as a reference surface for all subsequent tasks. Unfortunately I didn't take any photos of this, but I just used a flycutter to flatten the "ways" on the bottom, then used an end-mill to clean up the center channel. I then used this bottom surface as a datum plane to mill the sides roughly square and the top roughly parallel.

At this point I discovered just how janky the cheap milling vice I purchased is — even with the quill of the mill trammed within a thou of the mill table, the vice itself was quite a bit out of tram (several thou). Sigh. Not a big deal at this point where I'm just rough milling. I'll deal with it later.

Next I milled the tee-slots in the rear:
IMG_0463.JPG

After getting things in better tram, I used my nice carbide end-mill to better clean up the top (notice the vacuum sucking up swarf — cast iron is messy messy messy and even with ways covered it tended to get everywhere):

IMG_0466.JPG

Next I cleaned up the sides a bit more (bad practice having the clamp jacks over a slot like that — should have used pieces of scrap to span the gap):

IMG_0469.JPG

That carbide end-mill sure leaves a beautiful finish on the cast iron.

Now I was ready to start on the dovetail slot on the bottom. First I used some quarter-inch dowel pins and a micrometer to carefully measure everything on the original. Distance from the side to the bearing (non-gib) side of the dovetail, and distance between the dovetail sides. I also depth mic'ed the distance from the bottom bearing surface to the non-bearing parallel inside surface.

Once again I should have taken pictures of the measuring. I'll post some pics of the process tomorrow. The only remotely clever bit was using an adjustable parallel to measure the distance between the two dowel pins.

I used the straight carbide endmill to widen the slot roughly to size (to my great annoyance, I actually overshot a bit, but fortunately it was on the gib side). Then I got out the 60 degree dovetail cutter and went to work:

IMG_0470.JPG

Because my workholding kind of sucked (I should have just clamped down on the top surfaces, but somehow convinced myself I didn't have room and needed clearance on top) I took very light cuts each pass.

After I had both sides cut I just had to try it out, of course, to ensure I hadn't done anything wildly wrong to this point:

IMG_0473.JPG

It fit great, and more importantly, it passed my very basic tests:

  1. I put a mag base dial indicator on top, and measured the deflection on a faceplate as I slide the top-slide for and aft (while pushing the whole top-slide to the right by hand to ensure it was bearing on the dovetail surface). Total deflection was just two or three tenths over about 5.5 inches.
  2. I took the short gib from the original and ensured that there was room to slide it in on the right side with very little room to play. (I haven't machined the new long gib yet, so it won't fit vertically.)
That's as far as I've gotten so far. I will finally be able to get into the shop tomorrow to start on the remaining work:
  1. Machining the angles on the short sides of the gib.
  2. Boring and tapping the holes in the right side for the gib screws.
  3. Boring and pressing a locating pin on the right side of the casting as well as a corresponding hole in the gib (to prevent it shifting fore and aft)
  4. Machining the circular tee-slot to attach the compound.
  5. Boring a press-fit hole for the center locating pin for the compound (and pressing in the 0.5" pin)
  6. Boring and tapping the workholding holes on the top of the slide
  7. Machining appropriate bits to attach the nut for the crossfeed screw.
  8. Final lapping and scraping of all bearing surfaces (something I've never attempted)
  9. Doubtless dozens of other things I'm forgetting (like painting — God I hate painting)
Whee!
 
Last edited:

Ulma Doctor

Infinitely Curious
H-M Supporter - Gold Member ($25)
Joined
Feb 2, 2013
Messages
152
Likes
4,696
#2
nice work, i'm looking forward to the progression.
 

clivel

New Member
Registered
Joined
Apr 29, 2014
Messages
27
Likes
5
#3
It looks great so far Rex, I am following along with interest as I would eventually like to do the same for my Logan 200.
One question though, the swivel area on the original Logan cross-slide is raised above it's surface, is the new casting thick enough to ensure that the top-slide won't be sitting too low?

As I was typing this it occurred to me that rather than trying to cut the circular t-slot, it may just be simpler to look out for a South Bend top-slide instead.
Clive
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#4
... is the new casting thick enough to ensure that the top-slide won't be sitting too low?
Definitely. Actually, even after milling a considerable amount off the top and bottom I've left it a little thicker than the original (I'll have to readjust all my QCTP holders regardless). Original is about .900" from top raised lip to bottom surface. When I'm done I expect the new casting to be just over an inch.

I'm also enjoying the challenge of milling it for the stock Logan compound. I've not seen that documented anywhere, so I thought I'd give it a shot.
--
Rex
 

eeler1

Dang, buggered that up too!!
H-M Platinum Supporter ($50)
Joined
Mar 7, 2014
Messages
436
Likes
190
#5
The gib on mine has indents where the tightening screws are located, instead of a pin to prevent it slipping. Might be one less hole to drill in that cast iron. Just a thought.

Nice write up and pics. I'll be watching to see how it works out.
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#6
The gib on mine has indents where the tightening screws are located, instead of a pin ....
George Thomas felt the pin important enough that he devoted a few pages of his book (The Model Engineers Workshop Manual) to the topic!

"The usual arrangement is for the gib-strip to be held into contact with one side of the dovetail slide by means of pointed screws which touch the bottoms of dimples as shown at (1). These would be quite effective if the slide never had to move, but movement is what the slide is for! When the slide is wound along in either direction, the frictional drag against the gib-strip will produce a wedging action at the tips of the screws which will, in turn, tighten the slide. There have been many complaints on this score from readers in the past and the remedy is a simple one — fit a dowel into the gib-strip and so prevent any end movement in relation to the screws."
IMG_0546.JPG

Makes sense to me, so I'll add a pin as he suggests (and I note that my old cross slide did have a pin, despite the fact that the machining "does not readily lend itself to quantity production methods").

That chapter also reminds me that I want to add gib locks as well (added to the list). I'll probably add two locking screws, fore and aft.

(That also reminds me that I want to make a handwheel to manually turn my feed-screw on my lathe. That will allow me to do precise movements in Z along the bed by simply engaging the half nut.)

I milled the bevels on the gib this morning. I'll post photos after lunch.
--
Rex
 
Last edited:

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#7
Here's how I used 0.250" dowels to measure the original cross-slide:

First I measured used a depth mic to measure the distance from the bottom surface to the inner surface. Then I measured the distance from the side to the edge of the dowel. I just milled the bevel in the new slide at the same depth, and kept moving the cutter horizontally each pass until the side t0 dowel-side distance on the new part measured the same as the original.
IMG_0528.JPG

Then I used an adjustable parallel to span the gap between the two sides. Then I mic'ed the width of the parallel. Again, I milled the new part until this distance was the same.
IMG_0529.JPG
 
Last edited:

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#8
After milling the dovetail in the bottom of the new casting, I took some time to lap the bottom using coarse sandpaper on my surface plate (with water as a lubricant).

Next up was to mill the bevels on the gib. I had to decide whether to build a one-time-use fixture to hold the gib, or just use available tooling and figure out some way to hold the gib at the required angle to the tool. I opted for the latter.

The simplest thing I could think of was to again use dowels and my adjustable parallels (handy little suckers):
IMG_0532.JPG

This isn't the most secure workholding in the world, but I figured it would suffice. At first I only hand tightened the parallels by squeezing the wedges with my fingers, but eventually I wised up and started tapping them tight with a small tack hammer. Also, I eventually learned that (unlike the picture shown) I should ensure that I locate the outermost dowels as close to the front and back edges of the slide as possible (to provide better support at the ends of the gib).

Then I took extremely light passes (0.005" at a time) with pretty slow feed rates (power feed). I was careful to mill in the correct direction (table moving from left to right, with the cutter moving from top to bottom as photographed above) so that the gib was pushed back into the dovetail as the leading edge of the cutter hits the gib.

It was probably unnecessary to mention this, because only a complete idiot would risk throwing a part just to save a little time by milling in both directions and taking too heavy a cut.

IMG_0533.JPG

Ahem.

For what its worth, I'm very fortunate that I didn't chip my expensive carbide end-mill or (much worse) injure someone (me!) when the part was thrown. Even though I only had the slide lightly clamped, I was still surprised that there was enough force to pull it out of the clamps.

Lesson learned. This was when I got out the hammer to better tighten the wedges and started taking my time with light, light passes. I even slowed the feed a bit more once I started taking wider cuts as the quill was lowered.

Here's what it looked like as I was taking 0.005" at a slow feed rate (just to show how little I was actually taking off each pass).

On the first edge, I didn't mill down to a sharp knife edge. I left a tiny little bevel on the edge to ensure that I had enough material to mill the other side. I figured I'd be knocking the sharp edges off with a file when I was done anyway.
IMG_0536.JPG

For the other edge I just flipped the part and stole the idea from Paula on the South Bend forum to use some 3/32" rod as a spacer to lift the part enough to mill. Then rinse and repeat.
IMG_0537.JPG

Like spelling "banana," the only tricky thing about the second edge was knowing when to stop. :)

I wanted to ensure that the gib was narrow enough not to bind top-to-bottom in the slot, but I didn't want to mill off any more than necessary. This didn't need to be a super accurate measurement, I just didn't want the gib to bind. The solution was pretty simple, just use another piece of the 3/32" rod as a gauge on top:
IMG_0538.JPG

The camera angle is pretty awkward, but in person it was obvious that the gib was higher than the gauge rod (the square wasn't vertical): IMG_0539.JPG

I just kept milling until the square tipped the other way. Here's a shot from the other side once I was just about done (I think I took off another 0.005" just for good measure). You can clearly see that the squares are touching at top, but there's a gap at the bottom.
IMG_0543.JPG

Finally, here's a shot showing the finished gib in place on the slide (finished except for cutting it to length — I did that off camera):
IMG_0545.JPG

In this final shot of the gib in place, you can see one little detail I forgot to mention. When I cleaned up the casting scale in the slot on the bottom of the raw casting, I was left with a trench quite a bit deeper than the original part. At first I just started milling away on the roughly-formed ways to lower the gap, but eventually I chickened out. Instead of reducing the depth to final dimension, I reasoned it was okay to leave a little more "meat" on the sides. The trench isn't a precision bearing surface anyway, it just needs to provide clearance. Here you can clearly see the little "extra" gap I'm talking about (I don't think it will hurt anything):
IMG_0544.JPG

Next up is to bore and tap the holes for the gib screw, gib pin, and lock screws. I also need to make the lock screws.

Enjoy!
--
Rex
 
Last edited:

eeler1

Dang, buggered that up too!!
H-M Platinum Supporter ($50)
Joined
Mar 7, 2014
Messages
436
Likes
190
#9
I had no idea, was wondering why you were doing it that way! I'll defer to George.
 

wa5cab

Downloads Moderator
Staff member
H-M Platinum Supporter ($50)
Joined
Dec 25, 2011
Messages
4,363
Likes
1,075
#10
Rex,

The height of the underside of the cross slide is important (I won't say critical). The cross feed nut attaches under there and the threaded hole in it must line up with the height of the cross feed screw. You can always shim down. But you can't shim up (you can't buy negative thickness shim stock).

Also, when deciding where to put the hole to mount the cross feed nut, be sure that there is adequate clearance for the nut to run off of the screw threads before it runs into the top of the dovetail area. The gap between the dovetails sure seems to start a long way back. And also be sure that the nut runs off of the end of the feed screw before the cross slide runs off of the dovetails or into something.
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#11
You can always shim down. But you can't shim up (you can't buy negative thickness shim stock).
Joke #1: "If you cut a rope to0 short, you can always splice some more on, but if you cut it too long there's nothing you can do about it."

(Of course there is a "negative shim stock" equivalent. It's called an "end mill." ;-)

... be sure that there is adequate clearance for the nut to run off of the screw threads before it runs into the top of the dovetail area. The gap between the dovetails sure seems to start a long way back. And also be sure that the nut runs off of the end of the feed screw before the cross slide runs off of the dovetails or into something.
Joke #2:

"Ask me what the secret is to telling a great joke."

"What's the secre—"

"Timing!"

I'll post some photos shortly that explain what I mean here. I'm pretty sure I've got a way out, but I'll post some photos shortly that explain what I mean.
 
Last edited:

Silverbullet

Gold
Registered
Joined
May 4, 2015
Messages
3,419
Likes
1,671
#12
I also have a 11 inch Logan lathe. I love that little old girl I think mine would like the same thing . Adding room for tooling on the back is nice to have. I always wanted to add a taper attachment to her too. So maybe I'll do both if I can ever get the time . Too many projects .
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#13
Today's lesson is: don't try to do too much in one session! (You'd think I'd have learned this lesson by now.)

I was delayed getting into the shop today due to so some money chores taking far longer than seemed reasonable.

So I was both feeling rushed and in a foul mood at the same time when I started work on the slide today. The results were predictable. I only wish I'd read Robert's last note before getting started (though now that I think about it, I doubt it would have made a difference).

Before I quit yesterday, I bored and tapped 10-32 holes on the gib side for the gib screws and lock-screws. Andy's drawing called for nine evenly spaced holes, but since he didn't include either lock screws nor a pin, and since my slide is precisely 11" long, I thought I'd make my life easy on the DRO and tap ten holes spaced exactly 1" apart (at inches 1 through 10 from the right hand side:

IMG_0555.JPG

Then I used my adjustable parallels yet again to hold the gib in place as I drilled a hole for the pin, and marked the locations for the detents with a transfer punch. I'm using 1/8" dowel pin to pin the gib, so I first drilled a 7/64" hole all the way through the side of the slide and through the gib. The pin hole was exactly 7.500" from the left end as seen in the photograph below. I then used a transfer punch to mark the locations of the previously tapped 10-32 holes into the gib.

IMG_0556.JPG

Next I removed the gib and enlarged the marked locations with a prick punch. I later enlarged these detents on the drill press with a random large drill. Probably overkill to have both a pin and depressions for the gib screws, but overkill is my middle name. After drilling the depressions, I lapped the gib with sandpaper on my surface plate to remove any surrounding areas of metal that were pushed up by the process.

IMG_0557.JPG
IMG_0558.JPG

Next I broke out my "under/over" reamer set, and reamed the hole in the slide one thou undersized (0.124"). The hole in the gib needed to be oversized for a slip fit, but I couldn't use the slide itself again to hold the gib in place (using my trusty adjustable parallels) because I needed a press fit in the slide itself.

(Here, right here, is where I should have called it a day, cleaned the shop, had a beer and a good meal with the family, then had a good night's sleep. Sigh.)

Here's the first questionable decision of the day (fortunately it ended without incident): Unsurprisingly I didn't feel up to milling a fixture just to ream one hole larger in the gib, so I decided to free-hand it. I chucked a 0.126" reamer in the mill, broke out a pair of heavy leather gloves, and manually held the gib roughly in proper 60 degree orientation (figuring a reamer is reasonably self guiding as long as I hold it close, and I only need +/- 0.005" or so anyway). I'm not sure which would be more likely to grab, a twist drill or a reamer, but using a reamer with a moderate speed on the mill and the leather gloves I managed to enlarge the hole without so much as a scratch, much less a trip to the E.R. Whew!

By now I was in full-on, damn-the-torpedoes-full-speed-ahead mode, so I decided it was time to press in the gib pin. I don't actually own a press, but hammers, punches, and vises I have in spades, so here we go!

My dowel pins were considerably shorter than the depth of the hole, but I figured after driving in the pin as far as it would go with a vise, I could use a pin-punch to drive it the rest of the way. Wrong! Hardened against hardened is always a bad idea. I had exactly zero success driving the pin any further with a punch, but I did manage to make a beautiful couple of dings on the side of the slide.

A short walk later (there may have been some cursing involved) I realized that I should have just pressed the pin in from the other side (of course!).

At this point I had a (short) pin pressed in such that it was just proud of the side of the slide (with a couple of gorgeous "newbie tattoos" surrounding it) and nothing extending into the dovetail. After a head scratch, I realized that pressing in another pin from the other side would push the first one out sufficiently to grab onto it and remove it, so I put my steel jaws back on my vise (I normally keep my homemade copper jaws on the vise), grabbed a nut, and had a go:

IMG_0560.JPG

Worked just fine for the first sixteenth of an inch or so. After removing it from the vise to inspect progress, and then re-setting to push it the rest of the way in I had some trouble. The first sixteenth moved without severe pressure, but now it wasn't moving. I took it off again to inspect and the inner pin seemed to be going in straight. Nothing seemed amiss so, or course, I just assumed it needed more pressure (of course!).

Remember that little extra depth I had in the dovetail slot? (Last photo in comment #8.) In re-inserting the part into the vise, I managed to put it in deep enough that the vise jaw was catching on that step. So by cranking harder all I was managing to do was bugger up the outside (and bottom) of the slide with a nut-shaped outline — this came back to haunt me later.

Eventually I realized what was going on, and lifted the part a littler higher in the jaws. Then it was smooth sailing: I got the inner pin pressed in as far as I could get it with the vise jaws, and the outer pin was pushed out enough that I could grab it with the vise and remove it by taking a dead blow hammer to the part itself.

I could only push in the inner vise pin so far from this direction, and it had mushroomed slightly from the pressing, so I broke out a dremel tool and diamond bit to have at it. After about ten minutes of "fettling" the gib seemed to fit quite well, with no discernible slop. Joy!

I took the slide with the gib in place over to the lathe and tried it on the saddle. It slide on nicely until it got to the pin, then it bound slightly. Not enough to prevent it from sliding, but clearly it was binding and something was amiss. I thought maybe the pin was just slightly misshapen and keeping the gib from settling into the dovetail properly, so I broke out the dremel again as well as my optivisor with the extra loupe in front to really see what I was doing (no pictures of this — I look too ridiculous).

Back to the lathe. No joy. Still binding.

Eventually I copped to the fact that the "nut impression" on the side of the slide had actually created a couple of burrs or raised areas on the bottom of the slide (the bearing surface). After giving the slide a quick once-over by lapping again with sandpaper, I was extremely relieved to find it now slid freely with no binding. The burrs were raising the slide just enough to cause it to bind in the dovetails — it wasn't a side-to-side fitting problem, it was an up-and-down problem.

At this point I had to break out an indicator and see how I was doing. I was absolutely astonished to discover that by pushing and pulling on opposite corners with the slide fully retracted (completely covering the saddle) I only saw about 0.0025" total indicator movement. All the tramming effort appears to have paid off, smooth sliding with only a couple thou of play (before I insert any gib screws) is far better than I'd hoped for.

Woo hoo! Success. Time to clean the shop and call it a day.

Nope. "I just need one more hole in the slide to attach the cross-feed nut — that can't take too long!"

To cut to the punchline, I now have the nut in place, and the slide is working fantastically well with the cross-feed screw engaged and feeding smoothly, and with no discernible lateral play once I adjusted the gib screws.

Getting to that point will be another comment in this thread though. You know you've gone a step too far when you're not even willing to document the process in the same comment!

Onward!
--
Rex
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#14
Oh: Forgot to mention that I plan to use positions 2 and 9 of the ten holes for gib lock levers (that I need to make on the lathe). The remaining eight holes are for gib screws.

Also, it's important to put the gib pin someplace other than the exact center. It helps with "bi-lateral ambiguity" — between the dimples and the pin it's brain-dead simple to figure out the orientation for the gib whenever you're reassembling the slide.
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#15
I think mine would like the same thing.
While I can't claim victory quite yet, I'm increasingly convinced this is going to be a fantastically useful upgrade to my lathe. All I can say is "go for it!"

Andy's castings are very, very nice. Assuming my build is ultimately successful, I'll post measured drawings at the end of this thread. As should be obvious, I'm not working to precise drawings currently. Instead, this is effectively a prototype using measurements from the (far different) original part as well as (occasionally) dimensions from Andy's drawings. I don't want to post any drawings yet as I'm still making changes (AKA "mistakes").

I love my lathe too — it's absolutely my prize possession. I'm a user, not a collector though, so I have no qualms about replacing parts and modifying the original machine.

Andy also sells a casting to use as a taper attachment. It should be as simple as tapping a couple of holes in the back of the cross-slide to attach the taper attachment. I've tried to keep the design consistent enough that you can still use Andy's other castings without changes.

Regards,
--
Rex
 
D

Deleted member 473

Guest - Please Register!
Guest - Please Register!
#16
Nice write up! Thanks for sharing.

Now all you have to do is scrape and fit the slide to the saddle.....
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#17
Now all you have to do is scrape and fit the slide to the saddle.....
Actually, there was a whole lot more to do before scraping and fitting. Several adventures along the way that I'll start writing up shortly, but after a furious few days of working on it for 4 to 8 hours a day, I've successfully finished the cross-slide and gib! The compound slide fits beautifully and the cross-slide functions as well as I could have hoped. Now I'm ready for scraping and fitting:

IMG_0594.JPG

Woo hoo!
--
Rex
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#18
Okay, now that I've given away the punchline, here's the rest of the story (apologies to Paul Harvey).

Before reading the following, please remember that this is the continuation of the day I worked too long and made all sorts of mistakes. Still, the great thing about metal is that there is almost always a way out after mistakes (even if you have to braze on some more material).

I knew that all I needed to do was attach the acme nut and the slide would be basically functional as a boring table (i.e. without the compound slide). I just had to give it a shot.

The first thing to figure out was how far forward I wanted to put the hole to attach the cross-feed nut. I wanted to get as much travel as conceivably possible (hopefully reclaiming a little travel I lost with my home-made cross feed dials). I slid the nut onto the cross-feed acme screw and measured the distance from the dials:

IMG_0575.JPG

I measured multiple times and thought through it carefully before boring the hole, but 4.250" from the dial end of the casting seemed to be the optimal distance (with about 1/16" to spare).

I knew the new part was considerably thicker (about 0.100") than the original, though, so I had to get the hole in the nut positioned correctly vertically. So I measured the distance on the original part:

Screenshot 6:25:15, 5:12 PM-5.png

The distance on the new part was quite a bit thicker, but as I wise-cracked earlier I just needed to mill a pocket in the underside to the correct depth:

IMG_0567.JPG

WRONG! Wrong! Wrong!

Of course, as anyone taking their time would have realized, the dimension that matters is from the bearing surface to the mounting surface of the cross-feed nut:

Screenshot 6:25:15, 5:25 PM.png

So now I got to use both a negative and a positive shim. ;-)

IMG_0571.JPG

Finally, with the shim in place and the nut attached, the cross slide was actually feeding as I turned the crank. Success! Let's call it a day!

Whoops. Oh darn! (I may have used other words in the shop). When I screwed the slide all the way closest to me, it started binding about a quarter inch before hitting the dial:

IMG_0569.JPG

(Note the gap between the edge of the fixed part of the dial and the casting.)

Had I mis-calculated? Measured wrong? Do I need to move the hole?!! Argh!!

A few deep breaths and a walkabout later, I finally realized that the acme nut itself was hitting the curved part of the slot in the saddle. That was easy to fix with that most precision of tools, the bastard file:

IMG_0576.JPG

Now with the nut attached I could retract the slide all the way to the dial. Whew!

IMG_0577.JPG

As I think I already mentioned, even without the gib screws in place to tighten things up, I only had 0.002" to 0.003" of play even with my full weight pushing and pulling on opposite corners. With the gib screws in and adjusted, turning the crank was as smooth and silky as I could have hoped for. Now I could (and did) finally call it a day.

One further note: it was quite obvious that even with the gib screws adjusted, it was quite a bit tighter at the far side of travel than with the front of the slide closer too me. Close observation showed that the flat horizontal area of the fixed ways (on the saddle — not the dovetail sides, but the horizontal bearing surfaces) closest to me were visibly worn more than the areas further away.

This makes sense on such an old lathe since most of the time you are turning with the compound toward the front of the lathe. Since the farther side was less worn, it was effectively lifting the slide and tightening it on the dovetails. I'd felt the same thing since I owned the lathe, even with the original slide, and I thought for sure that I just hadn't done a very good job adjusting the gib screws. Now I know exactly why scraping and flattening the ways is such a big deal!

I tried to photograph the wear, but it was too hard to see with available light and the camera on my phone. Believe me, there was no way at this point in the day I was going to break out the SLR and a couple light stands!

Anyway, as long as the day had been, and as many screw-ups as I managed, I still ended with a functional boring table at the end of the day. Yay!

Note that I've re-used the beat up old screw to attach the cross-feed nut from the original part. Someday I may replace it with a new screw, but I'm more interested in utility than beauty most of the time, so we'll see if that day ever comes.

I've also marked the rough location where the compound will go. Unfortunately, the slot for the compound looks like it will interfere with some of the 5/16-18 tapped holes that Andy calls for in his drawing for other parts he sells (like ball turning attachments, etc.). I'll figure out alternate ways to attach things as I add accessories.

[By the way: Dykem Brite-mark paint sticks are awesome. The marks last much better even around oil and many solvents. My sweaty hands can erase the marks from a sharpie pen, but those paint-stick marks don't come off unless I make an effort to remove them.]

Onward!
 
Last edited:

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#19
Okay, today was the final day of machining. The first thing I decided to do was cut off the ears! Since I wanted to mount my compound further back on the casting, the ears looked funny. I figured that straight and square is probably more useful most of the time for workholding or whatever anyway.

IMG_0579.JPG

Next I needed to bore the 3/8" hole that holds the half-inch pin (hardened and press-fit) that the compound swings on. I used my 0.374" reamer to make it one thou undersized for a press fit.

Then it was time (deep breath) to start milling the circular tee-slot. The first step was to use a 5/16" end-mill to mill a circular slot (the slot is 3/8" — the smaller cutter allowed me to clean up the chatter on the sides). Plunge cuts are a lot easier on the machine, so I adjusted the stop and just plunged all the way around before following up with a clean-up pass to get rid of the ridges:

IMG_0584.JPG

Then I took the part off the rotary-table, flipped it upside down, and bored a 3/4" access hole to insert the square-headed bolts that hold the compound. I also need the hole to get the tee-slot cutter up into position. (Unfortunately, I forgot to take a picture of boring this hole, but it was a pretty simple operation.)

The tee-slot cutter has a neck that is narrow enough to fit in the 3/8" slot I milled, but the 1/2" shank wouldn't fit so I had to use my grinding wheel to grind flats on either side of the cutter until it would fit:

IMG_0586.JPG

I was a little worried that with so much of the shank removed, the R8 collet in my mill wouldn't be able to hold onto it very well, but that ended up not being a problem at all.

I was finally ready to start milling the tee-slot. The most puzzling part of the entire process (that had me mystified until I posted the question to the smart folks on this site). Okay, gibs locked in X, Y, and Z. Deep breath, look for anything stupid before I start removing metal — I've too much invested by this point to want to start over with a new casting.

This is only about the third time I've used my rotary table for anything. I'm not exactly the world's most experienced machinist — I bought my lathe a couple years ago and have only owned a mill for a couple months. I've tried to swallow my pride and publish all my mistakes as well as my successes so that others can avoid some of my more foolish errors.

Here's my initial setup when I started milling the slot:

IMG_0588.JPG

Now, notice that long bolt protruding from the table clamp on the right? See how far it is from the cutter? I've got tons of room, I thought. I'm milling a circle so there's no way it will interfere with movement, right? Wrong. The center of rotation is precisely 1.260" to the right of the cutter, so as I started rotating that thing clockwise I eventually ran into a problem. Unfortunately because I was removing a ton of metal in one swell foop with the tee-slot cutter (unavoidable) I had quite a bit of tool pressure and didn't notice the problem until well after that bolt hit the spindle and shifted the work significantly.

In my defense, with the captured cutter, there was no easy way to do a complete 360 with the quill fully lowered so I was completely dependent on my faulty thinking — there was no easy way to do a n0n-cutting pass with everything in position. Sigh.

Anyway, I had to reset and re-center everything with better work-holding (after hack-sawing the bolts shorter):

IMG_0589.JPG

That worked a treat (but notice the marred quill).

I had successfully milled a circular tee-slot with a captured cutter! That was pretty cool.

I've been wanting to make an aluminum sub-table for the rotary table to make this sort of workholding easier, but, of course, I wasn't willing to put this job on hold for that one.

Another shot of this the tee-slot milling:

IMG_0590.JPG

Next I had to put the old cross-slide back on my lathe to make the center pin for the compound. This was a pretty simple bit of turning (that I forgot to photograph). It was just some 0.500" drill rod, with a 3/8" stub for a short length for a press-fit into the cross-slide.

Only a complete idiot would overshoot to 0.373" instead of 0.376" as planned. Loctite to the rescue (laugh)!

I also hardened the pin with a torch. Just heated to cherry red and dropped it in a can of water. Chucked it back up in the lathe and cleaned off the blueing with scotch-brite. Pretty! (And hard.)

IMG_0594.JPG

Here's the underside (with the gib in place):

IMG_0599.JPG

And with the gib removed:

IMG_0600.JPG

Here's a terribly blurry photo of the gib pin:

IMG_0572.JPG

And finally, here's the assembled cross-slide with compound on the lathe itself:

IMG_0602.JPG

I left the milling marks from the 3/4" end-mill on top because I think it looks kinda cool. Originally I'd planned to fly-cut and maybe lap or scrape the top surface (maybe I will someday, but I'll have to remove the compound pin with heat first).

Obviously, the first job for my new cross slide is to turn down the gib screws a bit so they don't stick out (as well as making lock screws) but overall, I couldn't be happier.

I do plan to scrape and fit the dovetails and ways, but since I've never tried my hand at scraping before I want to get some practice with a simpler project first (the transfer block casting I bought seems like the perfect thing). I also plan to create measured drawings of my final design (or at least the design I'd use if I did it over again) in case anyone else has a similar-sized Logan and wants to attempt the same.

This was far and away the most complex part I've made in my short time machining. Couldn't have done it without sites like this and some truly superb YouTube publishers (Mr. Pete, Tom Lipton, Tom's Techniques, the Keiths — Fenner and Rucker, the Tool and Die guy, Dan Gelbart, and many others).

Very happy with the result!
--
Rex IMG_0589.JPG
 
Last edited:

wa5cab

Downloads Moderator
Staff member
H-M Platinum Supporter ($50)
Joined
Dec 25, 2011
Messages
4,363
Likes
1,075
#20
Rex,

That's great looking work. And better than I could do I'm sure. But I have to ask one question as devil's advocate. In the first photograph in your previous post (showing a top view of the saddle with the cross-feed nut all the way toward the dial), are there still cross feed screw threads in the nut or did it just run off the threads?
 

hman

Active User
H-M Platinum Supporter ($50)
Joined
Feb 17, 2013
Messages
1,859
Likes
1,508
#21
Wowsers! Great job! And whatever mistakes you made on the way were of the non-fatal, low-cost learning variety.
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#22
Wowsers! Great job! And whatever mistakes you made on the way were of the non-fatal, low-cost learning variety.
Ha, thanks! Nietzsche learning.

Thanks. Just realized I still need to scribe marks for the compound. Like Paula, I will also scribe four lines at the four points of the compass. Then it's really and truly done.
--
Rex
 

jeff_g1137

Active User
H-M Supporter - Gold Member ($25)
Joined
Jul 31, 2013
Messages
305
Likes
86
#23
Hi
Very nice work, i will have to look into getting the castings for my lathe, a denford viceroy 10 x 22", the cross slide on my lathe as ears or wings.
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#24
In the first photograph in your previous post (showing a top view of the saddle with the cross-feed nut all the way toward the dial), are there still cross feed screw threads in the nut or did it just run off the threads?
If I understand your question correctly, the cross-feed acme screw is threaded almost the entire way back to the dial end. The threads continue under the covered portion of the saddle, so the nut still has all threads engaged. I'm not sure that question makes sense, though, because if it ran out of threads I wouldn't be able to retract the slide any further (since the remaining part of the rod is as large as the major diameter of the thread).

Did I misunderstand the question?
 

wa5cab

Downloads Moderator
Staff member
H-M Platinum Supporter ($50)
Joined
Dec 25, 2011
Messages
4,363
Likes
1,075
#25
No. I just didn't know that the Logan was originally built that way. On the Atlas machines, if you start cranking on the cross feed in either direction, the nut will eventually run off of the threads. So unlike with carriage traverse, if you engage power cross feed in either direction, the only way that you can hurt anything is to run the tool post into the work. The Logan carriage covers the cross feed screw much further toward the centerline than does the Atlas. Or maybe it sticks out much further toward the operator. On the Atlas, where the threads stop going toward the operator, the diameter of the screw reduces to the thread minor diameter or a little less. I was wrong in assuming that the Logan did, too. Learned something new. :)
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#26
Ah. That makes sense.

On my Logan (actually a Montgomery Wards 11" Powr-Kraft circa 1941) you can crank off the back side, but it's not possible to crank off the screw on the near side. If you look at the first photo in comment 18, the threads on the cross-feed screw continue well under the covered portion of the saddle. Since the lathe does have power cross-feed without a clutch, it does seem like a better design if it were possible to run off the screw on the near side as well. I could machine a new screw, but the saddle would also have to leave more room uncovered.

All in all, I love this lathe. To be fair, it's the only one I've ever owned. The only other lathe I've ever actually used is the Jet 14" at the local TechShop in San Jose.

My only small gripes with the lathe were:
  1. Dials read radially rather than diametric, and the dials were so small that they were hard to read. [Fixed with new hand-made dials!]
  2. The zero locks for the cross-feed and compound dials are just radial grub screws, which interfere with the view of the dials. I much prefer the axial twist-lock mechanisms on big-boy lathes. [A future project?]
  3. The cross-feed screw cover that screws onto the back of the cross-slide appears to be zinc or some other non-ferrous material — it won't hold an indicator base. [Fixed with the new cross-slide!]
  4. Reading the compound angle is a real pain. The witness mark on the cross-slide and the compass gauge marks on the base of the compound slide are both on the far side of the lathe where it's hard to see (even if they weren't old and covered in grime). [Partially fixed with the new cross-slide.]
  5. The quick-change gear-box interferes with the carriage feed handwheel when it's at the extreme left end of the lathe. Not a problem when using a chuck, but with collets it's a real inconvenience (I have to extend the compound slide much farther than I'd normally like for maximum rigidity. [No solution yet.]
Regarding 4: The existing compound angle gauge marks just go around the back half of the compound base. I'm starting to think about a new project to re-do the compass gauge marks on the compound base. I want the tics to go the full 360 degrees around the base, and I'd also like to make them higher contrast somehow. Some complete idiot was over aggressive trying to clean up the existing base with sandpaper and a wire wheel, and some of the tics are almost completely worn away.

My current thinking is actually to make a plastic collar that goes completely around the base (I really like the look and high-contrast of the Harding micrometer dials). If I had a manual engraving machine, I could just laminate some thin white plastic over a black plastic base and then just engrave the letters and tics. I could do the tics easily enough with my vertical mill, but the numbers will require some kind of pantograph engraving setup (unless someone has a better idea). I'm now on the lookout for a small, cheap, used engraving machine (or plans for the same). I'm also thinking about designing a small sliding vise with a pantograph for the vertical mill to use for engraving one letter/figure at a time (ambitious dreams).

Regards,
--
Rex
 

Redlineman

Active User
Registered
Joined
Jul 27, 2013
Messages
295
Likes
12
#27
Well;

Pretty brave stuff to undertake, and quite a nice result. Kudos! Dang... I've got to get my lathe done!!!!
 

eeler1

Dang, buggered that up too!!
H-M Platinum Supporter ($50)
Joined
Mar 7, 2014
Messages
436
Likes
190
#28
I saw a guy, here I think, make a protractor-like device for setting the compound, using the flat on the cross slide body as the reference surface. Kind of a stepped contraption, iirc. Been thinking about that since, like yours, I have to get a flashlight and magnifying glass to read the angle marks on the compound, and also read from the back side of the machine which means I can't put it against a wall. All your slots offer even more ways to do it like that.

I like your collar idea too, but would still have to figure a way to see it easily from the front. I'll be watching your progress on this. Thanks for the clear pics and write-ups.
 

Rex Walters

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Apr 21, 2015
Messages
211
Likes
226
#29
Just a quick update after actually using the new cross slide for a simple bit of turning. [I'm making an extended Y-axis crank bushing for my mill to get a little more travel — but that's a topic for another thread.]

It turns out I was over-optimistic on the amount of adjustability available with my quick-change toolpost holders (AXA sized offshore knock-off of an Aloris QCTP).

As I mentioned, the new slide is quite a bit thicker (taller) than the old slide. I didn't think it would be that big a problem, but I was wrong. Many of my tools bottom out when adjusting before getting to center hight. I actually had to grind away the top half of a parting tool yesterday, just to get it down to center height.

So I'm going to have to skim a bit more off the top of the new slide before engraving the witness marks for the compound. Because the tee-slots are already milled, though, I can't take too much material off the top of the slide before the bearing parts of the slots become too thin to use. I don't want to thin them much less than 1/8". I'm probably over-cautious since there is normally something on top for the clamping bolts to bear against, but I expect there will occasionally be times when I'm clamping something hollow on the tee-slots.

Since I've also already milled the dovetails on the bottom, I can't take material off from the bottom (the dovetail slots would become too wide).

I suspect I'll have to take some material off of the compound as well. This isn't the end of the world, though, as my compound has seen a lot of use — taking some material off the top of the compound would actually help to clean it up.

So remaining work on the slide includes:

- Adjusting the thickness/height.

- Adding witness marks for the compound protractor gauge (and re-marking the protractor on the compound somehow so it has marks the full 360 degrees around the compound instead of just in the rear).

- Scraping the dovetail ways flat on both the slide and the saddle. [I've been practicing scraping on my "transfer block" casting. I think I'm getting the hang of it.]

- Painting. [I'll definitely wait until I strip and re-paint the compound and saddle as well. Maybe someday. I hate painting.]

- Making a rear-mount toolpost holder. [That will be another thread.]
 
D

Deleted member 473

Guest - Please Register!
Guest - Please Register!
#30
Here's some pictures of the compound slide I did last year. Might give you a few ideas on placing the marks and stamping the numbers.

DSCN1688.JPG DSCN1698.JPG DSCN1706.JPG DSCN1708.JPG DSCN1712.JPG
 
[6]
[5] [7]
Top