Building Harold Hall's Simple Grinding Rest

stioc

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Starting this build thread to ask questions as well as help out anyone else out who might be thinking of building one. If you don't know who Harold Hall is, do a google search but he's an author of several machinist books and has a reputation for being a pretty smart fellow. He also has a youtube channel with a few videos.

Here's the link to his page about this particular project:


The grinding rest is in his book about Tool & Cutter Sharpening, fantastic book btw and I highly encourage a hobbyist to purchase one. It's only about $10 and the info was well worth it if you have any interest in keeping tools sharp. He has two designs of this rest; a simple rest and an advanced rest. This build is for the simple rest.



I chose the simple rest because well I figured it would take me less time to build and I won't lose my focus/motivation - which tends to happen to me on long projects. BTW, this gentleman did a great job documenting his build and that actually motivated me to make this project:


After reviewing the design in Harold's book several times I became comfortable with what each part does. The next challenge was converting the metric measurements to the US measurements. This including the stock thickness he is using as well as all the screws, fastners, taps etc.

Lastly, it was time to go shopping for the stock (primarily 1018 cold rolled), nuts and bolts etc that I did't have on hand. I also purchased a couple of tools that I thought would make my life easier. This included a 60 deg dovetail cutter, a couple of YG1 brand spiral flute bottom taps.

Here's the stock I purchased and the bolt holes etc that I decided to standardize on. I won't provide any spacing dimensions etc beyond the rough sizes because all that is in the book - in other words buy Harold's book if you want to build this :)

 

stioc

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Day 1:
I rough cut almost all flat stock on my bandsaw to size in mm using my digital vernier calipers (which measures in mm, fraction and decimal and converts between them pretty easily). I rough cut a few mm over to account for blade thickness and tracking sideways. Between measuring and cutting the pieces it took about an hr.



After that I spent another couple of hrs squaring the pieces up to their final dimensions (in mm)



 

stioc

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Day 2:
So far so good! Now that the stock is ready we can start machining. However, while I could've drawn this up and done it using CNC I decided to do this the old fashion way -well sort of, more on this later. I Dykem'd the pieces and did the layout work first.



Harold suggests this a relatively simple project for a 'lathe only' shop. He does recommend a drill press though. Now, I'm not a very experienced machinist by any imagination but I think without a mill with a DRO (CNC in my case) it would've taken me a long time to make. I highly recommend a mill with a DRO so that once you find the edge of a piece you can just move to various locations to drill holes, tap etc. Speaking of that:

STIOC's tip: I highly recommend some sort of a work-stop to make things go faster without having to find your x0y0 again and again. I also suggest making your x0y0 along the fixed jaw of your vise so that it stays constant even as the size of the stock pieces change. I realized this after I was 50% through the project lol I made mine top left and used a work stop.

OK on with the machining already. I decided to build it from the bottom up...the reason for me was because machining is one of many hobbies I have and the base pieces are relatively simple. So they serve as sort of a warm up, getting to learn my machines again etc. So I started with the angle base...since this is A36 which can be hard on HSS endmills I chain drilled it first and then created a slot.





The slot was supposed to be 1/4" (6mm) but since I drilled it with a 1/4" drill bit it took me a few passes with the 1/4" endmill to clean up the slot and in reality the slot ended up being closer to 3/8". This is what I meant by starting with simpler things to warm up lol. Thankfully this slot size is not critical as long as I drill the vertical piece's hole centered to this slot and use the correct fastner.

STIOC's tip: drill with a size or two smaller than the endmill itself if you don't want to oversize the slot.

The next piece, the vertical bar, is basically the same thing - a slot and a hole except I didn't chain drill since this is 1018 not A36. I only drilled a starting hole for the endmill since drilling is hard on endmills.

After that I made the height adjuster. This has 3 of countersink holes (one of these is from the back side btw) and then a large 30 deg countersink to serve as a ball seat. This 30 deg is tricky for a few reasons:

1. One your lathe has to be able to swing an almost 115mm length. I had to shorten the length off about 1/4" as I was literally a paper thickness or so away from hitting my lathe ways and I didn't want to convert it into a permanent gap-bed lathe.

2. I couldn't figure out a way to clamp this piece in a 4-jaw chuck either. So I had to use the face plate and think clamps. My clamp set for the mill were just too bulky and big.

3. The angle and size are somewhat critical. Lastly you have to center the work which doesn't have to be super precise...









It was definitely a pucker moment in case the setup slipped but 120RPM, .005" cuts and lots of patience won this game. Now I have to make another one to match... :eek 2:
 

Technical Ted

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Here's a link to my post that shows more of the accessories that go along with the rest. I also built the advanced rest which I found much easier to setup, but they both work fine. Now I have a KO Lee tool and cutter grinder so they don't get much use, but they were very nice and fun projects to make.



Nice detailed post. Have fun!

Ted
 

Jubil

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Great write up and good, clear photos.
I also built the simple rest. I really like it, though it seems a little small and delicate. Very interesting project. I was thinking of building another one and scaling it up a mite. Probably won't get much use, except for hogging off, because I have a t&c grinder. But I can see it being used for grinding things other than cutting tools.
Thanks for posting.
Chuck
 

stioc

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Thanks gentlemen! I see you guys eventually moved on to the big-boy toys with your T&C grinders. I've had my eyes on the Chinese Deckyl clones but can't find the 5c version for under $500. However, being a minimalist at heart I figured this tool rest should function well for my needs. As for the accessories my plan is to build none because:

1. I have 5c collet blocks, square and hex to hold end mills and such in those.
2. I have a Phase 2 end mill grinder to grind the sides of the endmills
3. I have a Drill Dr 750X for grinding the drill bit ends
4. I can use my original lathe toolpost (the non-quick change type) or even the AXA tool holders to hold the tool bits

Again this is just my thinking, once I build it and try these accessories with it I may or may not change these statements :)
 

stioc

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Day 3:

Today was the day to hopefully finish the base and in my mind the first 30% of the project (dovetails being another 20%, table being 25% and the leadscrews being the final 25%).

So today included making the second piece, the head clamp and the clamp spacer. The head clamp requires a few holes and a matching ball seat. This piece (no through hole on this one but I drilled it part way) is smaller and on the contrary required more careful clamping because the clamping similar to the first one shifted when I tried to take a cut. I rearranged it such that it's 'boxed in' and not just clamped down. This worked and the piece was completed.



The clamp spacer has to be measured for distance before cutting, truing and then two #6-32 holes drilled and tapped. This completed the base.



 

brino

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Great write-up and photos.
I am "Watching".
popcorn.gif

Thanks for sharing this!
-brino
 

Janderso

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So that's how you do it.
Well done! Great thread and well documented.
 

Technical Ted

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Just a note... you don't need a dovetail cutter, as you listed in your shopping list post, to cut the pieces that make up the dovetail (if you follow Harold's drawings anyways). Just tilt the pieces at the correct angle and use an end mill or whatever.

But, you can use a dovetail cutter if you so choose, but I'd save the cutter for when you want to make Harold's advanced grinding rest. ;)

Ted
 

stioc

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Great write-up and photos.
I am "Watching".

Thanks for sharing this!
-brino
So that's how you do it.
Well done! Great thread and well documented.
Thanks for following along! I hope it's helpful to anyone else considering building one because I certainly had a lot of figuring out to do on how to approach the whole metric vs. imperial deal while still following along the drawings. Also Mr. Hall (who btw is 86 yo now as of 2019!:encourage:) doesn't do much hand holding in his style of writing. He does provide a few helpful tips on the tricky bits but that's about it- I must admit though that it actually makes the project more fun and rewarding!

Just a note... you don't need a dovetail cutter, as you listed in your shopping list post, to cut the pieces that make up the dovetail (if you follow Harold's drawings anyways). Just tilt the pieces at the correct angle and use an end mill or whatever.

But, you can use a dovetail cutter if you so choose, but I'd save the cutter for when you want to make Harold's advanced grinding rest. ;)

Ted
Funny you mention that because guess what I was just working on? Making sure my math/plans line up. Certainly not necessary but I'm nowhere near my shop and had some time during lunch - gotta make progress even if it's virtually lol



You're absolutely right about the dovetail cutter though. I just thought it would make things easier and I only need a hint of an excuse to buy more tooling! :)
 

stioc

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Day 4:

So now that the base is built. I can get into the fun part of this project i.e. the dovetail slide that moves the table in and out like the crossfeed of the compound. I started modeling the dovetail slide to make sure my dimensions in imperial are in check (they're not critical as long as the angle is exactly the same for both the inner and outer dovetails. This is where the dovetail cutter is so much easier and accurate.

However, before cutting the dovetails I decided to drill and tape all the holes in the dovetail parts first. This is where doing a little bit of calculation up front helped me out and I simply issued a few CNC G90 G0 x/y commands to drill all the holes in the exact same locations with the help of a work stop. Also glad I did the layout work because twice I issued the G90 commands and noticed the location was off compared to the layout because I messed up my calculations.









While waiting for the spiral flute YG1 tap I've been using the 1/4-20 tap (with much trepidation) from my cheap Harbor Freight set I've had for 5 yrs - I think I paid $40 for it and have used it many times but mostly in aluminum. It's worked fine so far even in this 1018 steel.



After all the drilling and tapping I located one of the parts on the vise to cut the dovetail. Mounted up the dovetail and realized I couldn't line it up right. I know I ordered a 3/4"x3/8" from All Industrial. Checked the stamping on the dovetail shank, it said 3/4 x 3/8 x 5/16 -ugh! the height is 5/16 not 3/8. I wasn't happy. I think @Technical Ted Ted jinxed me - I kid I kid LOL. This means doing it the manual way, which requires more setup time and more chance of error from not having repeatability. So my option was to order another dovetail and wait 2 days or forge ahead.
To be continued...
 

stioc

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Day 5

Well patience is not my strong suit so onward we go. I used an angle block to carefully set the angle and then checked/tweaked it as needed. This was repeated each time for four dovetails, it really wasn't bad, thanks to the 60 deg angle block.





This is the inner block that requires reverse dovetails on both sides.


Double checking the direction of the dovetails
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Honed all the edges


Everything fits


This is all the progress I've made thus far and it has gone pretty smoothly without me messing up parts and having to redo stuff. Still have lots of other pieces to do; namely bearing blocks, table, fence carrier, fence, leadscrews, handwheels...
 

stioc

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Day 6

Continuing where I left off last.

Made three identical bearing blocks:


Then started on the fence carrier but it's been kicking my @ss. It's like a T-nut with threaded holes on top as well as a hole running the entire width with the center portion threaded. The first attempt (shown on top) looks good with all the features but I went a few thou too deep on one of the slots - this will make it not sit flush.



So I had to scrap it and start over (cut another chunk of steel, machine it to dimension and then drill and thread)...it was going well



until the corn-cob endmill took a sudden bite...son of a #@$! I guess I got too greedy with my WOC at the DOC even though my feed rate was about half of what it should've been.



So I guess it'll be take 3 next time :lol_hitti So far I hadn't ruined any parts so this was the first. Also when I start to bolt these pieces down to the rest's top plate everything needs to align correctly, there's really no room for making imprecise holes etc. It's making me a bit nervous.
 

mattthemuppet2

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bummer! Looks like you were climb cutting - my guess is that there was a bit of slack in your table travel and the cutter self-fed itself a bigger bite than you expected. Try cutting the other direction next time and leave the climb cutting for a finishing pass with a nice 4 flute.
 

stioc

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You're 100% correct. I was indeed climb milling as I often do due to the fact that it creates less strain on the machine and the cutter. In this case, after retracing my steps from last night, I was in the cut when I accidentally hit the key to reverse direction. The CNC software is configured to take up the backlash amount on directional changes and that's when the cutter took a big bite.
 

mattthemuppet2

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I'm sorry, I didn't realise that it was on a CNC, that changes things a bunch. Glad you figured it out.
 

stioc

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Day 7

I did remachine the fence carrier block but didn't drill and tap the top 4 holes nor did I skim it flush with the top plate. Doing so at the very end will be better in my opinion.

Next I started mounting all the pieces to the top plate. This is sort of the moment of truth. If things don't line up that would be a bummer. I decided to start with the table's fine feed bearing block, these are all going to be #6-32 holes, the drilling and tapping is in the 1/4" thick plate but these are no through holes so the depth has to be controlled. Also need a plug tap, and I highly recommend the YG1 spiral tap I got, it cut like butter and evacuated the chips up like a drill bit does.



With the first bearing block in place I attached the center dovetail and then placed one of the side dovetails against it, making sure it was all square to each other.



Then came the second dovetail. I decided to fold paper 3 times and use that to leave a gap because the two dovetails were running a bit rough against each other. However, in hindsight I should've just made the holes in the two end dovetail blocks slightly larger to allow small adjustments and I should've done the same for the bearing blocks too...I actually did in the end because things were binding up.





This completed most of rest's top and the milling work. I still have to make a fence but next I want to start on the round/lathe parts.

 

stioc

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Day 8 (the lathe work):

Well I thought this was going to be somewhat of a more difficult task to turn leadscrews and graduated dials but I was done in 4 hrs and actually really enjoyed it. I just seem to enjoy the lathe work more than the mill work it seems lol



Used the tailstock die holder for the first time. This thing is slick but I was turning by hand so it was a slow going


For the longer leadscrew after I got 5 or 6 threads by turning it manually I decided to speed it up...to 600 RPM by gripping the die stock holder and hitting the switch (making sure I was clear of everything and I had an exit strategy if things went sideways). I don't recommend this if your lathe has a powerful motor or you're cutting a 'stronger' thread. I had purposefully undersized the major diameter by .01" so it threads easily and I can actually stall out the motor on my lathe with my hulk grip (the belt slips). This worked so well, how well? literally 3 seconds and I was done!



Then I made graduated dials, each line is .0013"



There's everything completed...I can see the light at the end of the tunnel now!


 

stioc

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Day 10

The build of the rest is finally complete. I wouldn't call this project difficult but it took some time (and dedication) because it does have quite a lot of parts. While I had studied it well before starting and made sure I had tools, supplies etc ahead of time to carry out the project but I realized during the project that a few handy jigs and tools would've helped even more. One of the things I want to make is a better work stop, a AXA holder for the dial indicator (for doing 2nd ops, sometimes you can't avoid this) and add air to the lathe because it works so well on the mill. A vfd on the mill would be sweet...but I need to research what motor will fit my RF30, maybe replace the spindle bearings too.





First task was to true up my 10 yr old grinding wheel which I didn't realize how irregular it was until I did this



This was very dusty work and I should have done it outside. Even with the vacuum on this accumulated on the grinder cart:





Then I attempted to sharpen an endmill...which has a learning curve to understand all the angles and such so that will take some learning and practicing...now that I have the ability to do so in my shop.

 

ttabbal

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Nice! I'm eyeballing the advanced rest, but it will be a while before I can get to it.
 

stioc

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The advanced rest looks to be easier to adjust and use so it's a couple of steps above this one for sure. However, I figured it would take me longer to make too. I haven't yet had time to use this one properly but I think this will do ok for my current needs until I decide to get a real tool bit grinder.
 

pontiac428

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Nice work! That is a lot of parts. The rest looks very functional.

Keep resharpening that end mill. See how it cuts. Repeat. Grind it down to a nub. Once you find the right angles and timing of the flutes (just like a drill bit, only more steps) you'll be able to grind one in your sleep. You might want a good tool grinding wheel (Norton 38A 60-grit) for a better finish and to keep from heating up the HSS. Post up what you grind!
 

stioc

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Nice work! That is a lot of parts. The rest looks very functional.

Keep resharpening that end mill. See how it cuts. Repeat. Grind it down to a nub. Once you find the right angles and timing of the flutes (just like a drill bit, only more steps) you'll be able to grind one in your sleep. You might want a good tool grinding wheel (Norton 38A 60-grit) for a better finish and to keep from heating up the HSS. Post up what you grind!
Harold's grinding book covers lots of details which prior to making the rest were hard to visualize (I'm a visual person) but I think rereading those will make more sense. I just need more seat time :)

Thanks for the wheel suggestion! I'm thinking about make an arbor adapter and getting one of those fancy cup wheels...thoughts?
 

pontiac428

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Thanks for the wheel suggestion! I'm thinking about make an arbor adapter and getting one of those fancy cup wheels...thoughts?
A cup wheel is necessary to grind a flat using proper technique. The dressed surface of a conventional wheel presents a curve to the work. With a cup wheel, you can set up the grinder and rest like a Delta carbide grinder with the rest on the side. A flared wheel will give you an easier time with 4-flute end mills, but aren't great for lathe bits compared to a cup wheel. A bench grinder is made for 6" wheels direct drive, and a tool grinder is made for 4" wheels belt drive, so your surface speed may be slow with the smaller wheel. Cups and flares come in 5", too. You'll have to see what works.
 

Technical Ted

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Go here for Harold's website. Check the videos... he has them on using the grinding fixtures for grinding end mills and other tools. Lots of stuff on his site:


Ted
 

stioc

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So the other day I decided to give the grinding rest a try using a wood chisel as my test subject. The end on it is pretty well chewed up and rough.



I started by getting the end nice and square and that worked better than I expected


Next I set the angle using a 30deg angle block against the fence. The idea is to maintain the angle and feed the chisel straight while also keeping contact with the side of the wheel. One of those moments you need a third and a fourth hand.



The results were ok but not great, one end of the edge was sharper than the other. I didn't take a pic. However, despite my wishful thinking that I was done with the rest this made it pretty obvious to me that in order to take advantage of this rest I really need to make a couple of accessories for it also.

So, I started with the swivel plate because it forms the basis for several other tool holder accessories.

 

pontiac428

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Time to get yourself a cup wheel. Dressed surfaces do so much better than the sides of a standard wheel. Set up that rest to work like this pic, and you've really got something:
 
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