Tool Post Holder

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
661
I am doing the boring on my lathe. Don't have a boring head for my mill/drill. I use a telescoping gage and a micrometer to measure the ID of the hole that I am boring. I am getting better at it. I now get consistent measurements. My measurements are smaller than the actual ID. How do I know this? As stated in a previous post my measurement of the ID of the hole is smaller than my measurement of the OD of the post yet the holder fits on the post. So the ID has to be bigger than my measurement.
Hi Mick,

Try doing it the old fashioned way with inside calipers and a micrometer.
 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
On my first holder for my 1/2 & 5/8 boring bars due to a lack of room I used a 1/4 x 20 bolt as my clamping bolt. It only takes 1/4 turn to clamp the holder tight to the post. And it takes a lot of force on that 1/4 turn. On my next holder for my small boring bars I had more room for a larger 3/8 x 16 bolt. The force required is a faction of what was needed for the 1/4 x 20 bolt. Slightly less than a 1/4 turn to clamp the holder to the post. I now know that a 5/16 x 18 bolt will fit on the large boring bar holder. If I can figure out a way to fill the existing hole for the 1/4 x 20 bolt I will try to fit a 3/8 x 16 bolt on the large boring bar holder.
Moral of this is to use the largest bolt possible for the clamping bolt.
 

homebrewed

Registered
Registered
Joined
Jul 28, 2017
Messages
383
Moral of this is to use the largest bolt possible for the clamping bolt.
I would think the 20TPI threaded bolt has a greater mechanical advantage, so, all else being equal, it should be easier to tighten it down. Also, because of the finer thread, you would expect to turn it more for a given amount of "squish". I suspect you are mostly seeing differences between the two big holes you bored.

I used 10-24 bolts for everything on mine -- the closer and the 3 for holding the cutter in place -- and they work fine for me. However, my tool holders are made from 6061, not exactly an apples-apples comparison!
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
661
Hi Mick,

This is the way I measure a bore !

15-09-2018-001.JPG
Outside spring calipers. If you buy a Chinese one, make sure that it has rounded ends, like small balls.
I've seen one that actually had tiny balls fastened on the ends of the legs.

15-09-2018-003.JPG
This is how you use it. Here I'm going for 35 mm.

15-09-2018-004.JPG
And here is the actual micrometer reading. Maybe 10 microns over.
 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
Today I finished boring the last of the center holes. Next chore is to mill the slots for the atlas craftsman tool holders. I will measure the holders again. From memory they were 13/16 high by 3/8 wide. I am thinking of making the slot .82 high by .40 wide. The slot will be 2 1/4 long. Milling the entire slot would take me a long time. To make it go quicker I thought of drilling most of the material away and then cleaning up the slot with the mill. Which way to drill the holes is the quandary. And what size drill to use. I think using a 3/8 drill and drilling two holes the length of the slot would be better than drilling a bunch shallow holes.

Suggestions please.
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
661
Hi Mick,

I just clamped it up in the mill vice and ran the cutter across six times taking 2 mm deep cuts. But yes drill most of the meat out if it makes it easier.

Another picture for you,
15-09-2018-011.JPG
Here I am about to take my third or fourth 2 mm cut. 12 mm four flute slot drill. Chinese HSS :)

25-09-2018-007.JPG
This is one of my Norman tool post holders. It goes from free to locked with about 1/4 turn of the cap screw.
 

homebrewed

Registered
Registered
Joined
Jul 28, 2017
Messages
383
This is one of my Norman tool post holders. It goes from free to locked with about 1/4 turn of the cap screw.
Out of curiosity, how does your tool holder lock to the post? I don't see a slit cut in the holder, so the locking principle appears to be a little different from most Norman-style tool holders.

BTW I like the nut you made -- it looks pretty nice.

-H
 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
Nice job on your tool holders. My boring bar holders are are a little on the rough side but work well. Mine also take only a 1/4 turn to go from free to locked. I have been using the two boring bar holders to bore the center holes on the remaining five holders. I have decided to complete one holder as a test run. I will try cutting the slot with just the end mill without drilling out most of the material to see how that works for me. I can hold all of the last four holders in my vise at one time.

IMG_3632.JPG

That way I can cut the slot in two of the holders at the same time. Then do the other two. I have been using the slowest speed on my mill in previous projects. For this I think that I will figure out what speed I should be using and see how that works for me.
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
661
Hi Homebrewed,

It uses the original design of the Norman tool holder and is the same as Rolls Royce use in their experimental workshop.
If you scroll up the post you will see the drawings that I posted showing the split clamp. Posts 48 and 54.

The nut was a scrap of free machining 25 mm AF hex bar. Drilled and threaded 7/16" BSF.
The shaping was done with a carbide wood router bit.

16-09-2018-010.JPG
The only reservation I have is that I only have 1/4" inch shank versions of these. I would have preferred a 1/2" shank one.
Run at around 800 rpm in the mill and about 600 rpm in the lathe.
This picture was when I did the Norman Tool Holder shaping on the back edges.

20-09-2018-1.JPG
Here I am using the router cutter to round off a brass tip on the end of an M6 screw.
 
Last edited:

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
661
Nice job on your tool holders. My boring bar holders are are a little on the rough side but work well. Mine also take only a 1/4 turn to go from free to locked. I have been using the two boring bar holders to bore the center holes on the remaining five holders. I have decided to complete one holder as a test run. I will try cutting the slot with just the end mill without drilling out most of the material to see how that works for me. I can hold all of the last four holders in my vise at one time.

View attachment 276819

That way I can cut the slot in two of the holders at the same time. Then do the other two. I have been using the slowest speed on my mill in previous projects. For this I think that I will figure out what speed I should be using and see how that works for me.
Thanks for the picture. Be very careful holding several pieces like that in your vise. I personally would not do that. You cannot guarantee that the work pieces have faces flat enough to grip each other. At best I would only hold two, and even then use some cardboard between the vise faces to ensure that they were both gripped securely. Also tap them down so that they are sitting flat on the vise bottom.
 

homebrewed

Registered
Registered
Joined
Jul 28, 2017
Messages
383
Ok, I got it now. The main body of the holder is NOT split, it's the pin. It makes for a very clean look! I'll have to give it a shot -- slitting the holder is a slow job, at least the way I do it....
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
661
Hi Guys,

I think that most of the articles that I've seen put a slit in the block and squeeze it with a clamping screw, did it that way because it was easy to write an article for publication without putting people off because it was hard to make. Forty or fifty years ago it would never have been done.

I used to have a copy of the original drawings for the Norman Tool Holder, in those it was a split clamp as in my drawing.
As I mentioned to Mick, splitting the block means that you only have two points of contact on the post. Using a split clamp actually has three, but those contact points cover a much larger area and thus greater rigidity.

One other important point that I have just remembered. When splitting the clamp, make sure to deburr the edges of the cut ! If you don't the burrs will cut into the post and make the movement rough.
 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
Started cutting the first slot in a tool holder. 1/2" four flute end mill and 90 rpm. I know probably way too slow but then I am a newby. Depth of cut is 0.010. My mill/drill doesn't seem to like cuts deeper than that. Here is my set up.

IMG_3633.JPG

As I make a cut the table jumps back and forth by the amount of the backlash in the table. It feels like climb milling. Is this normal when milling a slot? Or am I doing something wrong.?
 

pacifica

RGL
H-M Supporter Gold Member
Joined
Jan 2, 2018
Messages
274
Started cutting the first slot in a tool holder. 1/2" four flute end mill and 90 rpm. I know probably way too slow but then I am a newby. Depth of cut is 0.010. My mill/drill doesn't seem to like cuts deeper than that. Here is my set up.

View attachment 277100

As I make a cut the table jumps back and forth by the amount of the backlash in the table. It feels like climb milling. Is this normal when milling a slot? Or am I doing something wrong.?
tighten the gibs a little?
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
661
Hi Mick,

As Pacifica says, tighten the gibs, you have too much slap in the table. 90 rpm is way to slow for a 1/2" inch cutter !
Make sure you nip the quill as well, you don't want the cutter to pull the quill or the cutter to pull out of the chuck collet.
As far as depth is concerned 10 thou is barely a scratch.

But since you are learning, try 20 thou (1/2 mm) and see how the machine behaves, increase the rpm's to say 400. That mill has a substantial round column, so if the table is tightened up you should easily be able to do a 2 mm (80 thou) deep cut, which I can do with mine.

Also its nice to see that you have taken my advice about not ganging up workpieces.

Keep me informed about how you get on.
 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
I checked my backlash and it was way out. Undid the lead screw on one end and slid the table to one end to expose the lead screw nut. Found that one of the bolts that holds lead screw nut in place was loose. Tightened everything up and my backlash is back to its usual 0.005. In process of tramming the vise and then hopefully I can get the tool holder close to where it was. I don't have to be absolutely exact on the tool holder because I was milling about 20 thousands from my line on one side with lots of room on the other side of the slot.

I'll try the faster speed and deeper cut to see how that works.
 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
Tightening up the lead screw nut solved the problem. The faster speed and .020 cuts worked well. Baron thanks for the suggestion. I got the slot cut. Only have 4 more to go. I'll start on those tomorrow morning.
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
661
Hi Mick,

Thats good to hear ! But you are going to have to watch that bolt. If its come loose once it will probably come loose again.
Some of the threads on both the bolts and in the holes leave something to be desired in terms of fit. That non setting thread lock could be used with advantage.

However do check the gibs, no point in them being too loose if its going to compromise your ability to cut material properly. Check them at the ends of the table travel, that they don't get too tight there. The most wear is usually in the middle and that is where the table will be at its loosest.
 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
Finished the last of the slots this afternoon. The first slot took me almost 3 hours to cut. The last one this afternoon took just under 30 minutes. I think that I am getting better. Time will tell. Have 30 holes to drill and tap and five slits to saw. The atlas/craftsman tool holders that I have are mostly either 3/4 or 13/16 high with some just a littler higher. I decided that a slot to fit the highest ones did not leave enough thickness for the set screws to screw into to hold the tool holders. So I am milling all of my atlas/craftsman tool holders down to 3/4" high. I am leaving the bottom edge as is and only milling the top edge. That's all for today.
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
661
Hi Mick,

I'm watching and listening ! You know what they say about practice !
 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
I basically destroyed two end mills cutting the slots. Before cutting the slots I did my usual online research. There seemed to be two camps. One was don't use an end mill to cut slots/key ways because you will break the tips off of the end mill. Especially if using a four fluke end mill. The other camp's response was nonsense. No problem cutting slots/key ways with end mills. I am with the don't do it camp at this point.

As I was cutting the second slot I noticed a line in the side of the slot. After I finished the slot I took out the end mill and some of the tips were broken off. I attributed this to the problem that I had had with the lead screw nut being loose and the table moving around. Chucked up a new end mill and cut the three remaining slots. I didn't notice any problems during these cuts. Looked at this end mill when I was done and again some of the tips were broken off.

Did some research on sharpening end mills to see if I could save these two end mills. Found that without ridiculously expensive machines sharpening an end mill is not possible. The only advice was to save the damaged end mills for making rough cuts. Then through them away.

The next time I have to cut a slot/key way I will try the drill most the material away then clean up with an end mill method. I'll also look into key way cutters.

On a positive note I finished up one of the holders yesterday afternoon. Took 3 1/2 hours as I stumbled along. The rest will go quicker now that I have the process down. I will post some pictures when I get them all done and cleaned up.
 

pacifica

RGL
H-M Supporter Gold Member
Joined
Jan 2, 2018
Messages
274
I basically destroyed two end mills cutting the slots. Before cutting the slots I did my usual online research. There seemed to be two camps. One was don't use an end mill to cut slots/key ways because you will break the tips off of the end mill. Especially if using a four fluke end mill. The other camp's response was nonsense. No problem cutting slots/key ways with end mills. I am with the don't do it camp at this point.

As I was cutting the second slot I noticed a line in the side of the slot. After I finished the slot I took out the end mill and some of the tips were broken off. I attributed this to the problem that I had had with the lead screw nut being loose and the table moving around. Chucked up a new end mill and cut the three remaining slots. I didn't notice any problems during these cuts. Looked at this end mill when I was done and again some of the tips were broken off.

Did some research on sharpening end mills to see if I could save these two end mills. Found that without ridiculously expensive machines sharpening an end mill is not possible. The only advice was to save the damaged end mills for making rough cuts. Then through them away.

The next time I have to cut a slot/key way I will try the drill most the material away then clean up with an end mill method. I'll also look into key way cutters.

On a positive note I finished up one of the holders yesterday afternoon. Took 3 1/2 hours as I stumbled along. The rest will go quicker now that I have the process down. I will post some pictures when I get them all done and cleaned up.
You can sharpen the ends, not so easy the helix.
 

Dabbler

Administrator
Staff member
H-M Supporter Gold Member
Joined
Oct 11, 2016
Messages
1,329
Mickri, I have a friend that sharpens his 4 flute end mills, by hand at a normal bench grinder. It is one of the many skills it is possible to learn while progressing in machining. You won't ever get all 4 flutes cutting that way, but you can reuse a wrecked mill a long time that way.

Second, If you are messing up your end mills, carbide or HSS, you are doing something wrong. There are thousands of things to target here. But even on moderately hard steel (Rc 30 and below), HSS end mills will do the trick if you are careful. If you buy centre cutting end mills (which you should), in good quality, you can plunge mill your keyway, and then finish mill it after.

For 40 years I have been in the 'it isn't a problem to mill keyways and slots' camp. It isn't a lie, it just takes skill.

If you are trying to mill a slot in a very hard (Rc45 or higher) or carburized shaft, all bets are off. All that takes is a file to test, and if it skates, then a far more careful approach is required.

Another factor is your setup. With a tiny mill like you have it takes MORE skill to do a great job without wrecking tools. To reduce deflection in your column, take light cuts with a 3/8 end mill - it will result in 1/4 (approx) of deflection force on your column. You will need to run higher RPMs and take plunge cuts. Cutting using the X feed with a 1/2" end mill may be part of your problem.

Here's a good video on plunge milling:

 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
The material is 1018 steel. The slot is .400 deep by .750 wide by 2 1/4" long. I had the speed at 400 rpm and each individual cut was .020 or less following BaronJ's suggestion in a previous post. I don't know the feed rate but I wasn't pushing it. Just a steady flow. I first cut one long slot the width of the end mill down to .400 in multiple passes. I then widened the slot with conventional milling, no climb milling, to .750. Each cut was again .020 or less. I will try to take some pictures of the end mills.

I had watched a video but don't think that it was Tom's. I'll watch Tom's video. The video that I watched I didn't think was really applicable to what I was planning to do. The material was 1/4" aluminum and was being cut all the way through. It had you start in the middle by plunging all of the way through then going out to the edge and then going all of the way around. I was cutting a large, deep key way for all intents and purposes.

Cutting the slot had a feel to it like the end mill was alternating between conventional milling and climb milling.

I am open to any and all suggestions. I do not like damaging tools.
 

Dabbler

Administrator
Staff member
H-M Supporter Gold Member
Joined
Oct 11, 2016
Messages
1,329
On a small mill drill like yours (I owned a slightly larger machine than yours for 17 years - it can do capable work) I would have plunge milled to roughing depth, engaging 1/3 of the 1/2" cutter, cutting slowly with lubricant, I'd then advance about 1/4 the diameter and keep plunge milling until I had a nearly 1/2" slot. I'd then plunge mill the rest of it to roughing dimension. You have to be very careful on exiting the slot that you don't catch the cutter - you just cut with a little less pressure..

After that process I'd take the tops of the waves using conventional milling, taking about .010 cuts. Then I'd mill the final depth, not touching the sides. The last operation is to climb mill the last pass(es) taking shallow cuts, .005 with perhaps .333 engagement on each pass until I got the sides to spec.

Plunge milling isn't just for aluminum, or for shallow milling. I once milled cast iron where the guy needed a flat face in between two bosses. the contact area on the HSS mill was just under 2". He had broken 2 mills using full engagement. I plunge milled the surface using .010 steps, and then climb milled the final surface. It took a few minutes to do the job. He had been milling/failing for just under 2 hours.

So plunge milling is fast, uses only the END of the END mill, saving your helix for subsequent sharpenings. It creates far less side pressure on the machine as the only contact area is under the mill, not on the side of the mill. The downside is that you get impatient, and plunge too hard, the *ping*, a cutter will bite the dust!!!

It is possible to make a jig to resharpen the end flutes on a 4 flute end mill on your own bench grinder. There used to be a jig you could buy to do this, similar to a drill sharpening jig. I haven't needed one, because, well, (he said with some embarrassment, ahem) I bought 2 of those expensive sharpening machines you mentioned. What you need is something to hold your cutter to an angle, stop the cutter at an engagement on the grinding wheel, and allow you to advance the cutter for each flute.
 

mickri

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 31, 2016
Messages
850
One thing that I am not is impatient. I don't care if it takes me all day to do something that somebody else could do in minutes.

I had considered drilling out most of the material in the slot and only using the end mill to clean up the bottom of the slot and the sides. I decided not to because I was concerned about the end mill catching on the protruding edges left from the drilling. Especially on the climb side. I could envision a point on the end mill first hitting an edge in conventional milling and then as it rotated hit another edge in climb milling. In hindsight I probably should have either drilled or plunge milled out most of the material in the slot.

I have watched Tom's video on plunge milling. It seems like in most of these videos the machinist is always working with aluminum. I often wonder if what works in aluminum will also work just a well in steel.

This is something that will come up over and over. I plan to make a couple more of the holders. And when I modify the wood cutting band saw I recently purchased to cut metal I will have to cut a key way in a 5/8" shaft for the reduction pulleys. I do have a key way cutting. Have not checked the size.

I will look into the angles to clean up the end mills and give it a try. My thought process is that if something is already broken I can't make it any worse by trying to fix it. A lot of times I am successful in my fix.

Thanks for all your suggestions.
 
It can take up to an hour for ads to appear on the page. See our code implementation guide for more details. If you already have Auto ad code on your pages there's no need to replace it with this code
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock