Hand Crank Grinder Rebuild

[Chris Jackson]

As promised here's the first installment of rebuilding my new/old "CoolKutter" hand crank grinder.

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Picked this guy up for $30 on ebay a couple weeks ago...

Decided to build a Krenov like hand crank grinding station, so I picked up a Veritas Tool Holder/Jig and a fresh white oxide wheel.

Initial inspection of the grinder reveals that it is in working condition, I don't hear/feel any skipping teeth, 90% of the coating is still present, and runout does not appear too bad though the wheel that is installed must be tossed...all in all it feels like a well made American hand tool...

started my disassembly and noted that someone managed to inject this old guy full of colloidal graphite based anit-sieze!!! FYI for any of you folks out there looking to rebuild one of these old beauties DO NOT USE GREASE!! Grease is for bearings...helical, herringbone, and/or straight cut gearing should all be oil lubricated...I won't go into a diatribe about the engineering bases for this, suffice it to say it is for the same reasons that you do not grease your bicycle gears/chain. With a light load, single pinion and bull gear, straight tooth, setup like this, and occasional shot of T9 is more than enough lube.

Here's the dirty bits disassembled:

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I did lots of cleanup and inspections, and finally managed to remove all the old ant-sieze (what a pain)!! I went through a lot of Q-tips and alcohol!!

Used a lot for Rust Free as well, to clean up the fasteners. The bull gear and pinion teeth looked to be in great shape. Pinion teeth may have been a bit thinned, but nothing that should affect performance.

The fasteners needed some love, a little touch with a diamond file to remove old strip/slip marks and then a good dousing of the whole works with T-9.

One negative I did notice is that the hand crank bore where it mates to the bull gear shaft is bored slightly out of line, or has gone out of round with time/use...the fix would require either bending the handle slightly (risky) or reboring and sleeving the hole which seems a bit overboard for this project...so, I backed the handle off far enough where it would not create a rub to set the play in the bullgear a little bigger than normally necessary (maybe an extra .050") and it works fine...if only a little more loose than I'd like.

Here's the cleaned up bits:

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So, as you can see in the photos I also picked up a new white oxide wheel and a veritas tool holding jig...mounting those items to a stable base is the next step...I'm thinking a Baltic Birch ply slab that I can clamp to the bench.

Went to mount the wheel and realized that I should have measured before ordering!!! :eek: I picked up a 6" and the max the grinder will take is 5" without interefering with the clamp mechanism...so, two choices: 1. Mail it back to Lee Valley in exchange for a 5" and wait a week or so; or 2. whip out the diamond dresser and start turning it down to size...I chose the latter.

***Note: If you are planning to pick up one of these hand crank grinders sight unseen (ebay), make sure you clarify what the maximum wheel diameter/width/arbor it can accept; this will save you lots of time/suffering later!! (This model will take 5"x1"x1" Max)

So, I'm going to grind this wheel down tomorrow from 6" to 5" and build the base...mount the tool holder and test it out on a new plane/iron I picked up at the woodworking show in Dulles today...

More to follow.

[Mark Baldwin III]

How easily does it crank? I just rebuilt one this week and I got some bronze thrust bearings. The original set up had all steel washers and was a pain to turn. The bronze bearings helped out a lot. I also decided to go with a 4" wheel. I just have to get around to dressing it.

[Danny Burns]

As promised here's the first installment of rebuilding my new/old "CoolKutter" hand crank grinder.

More to follow.

Thanks for the post!
I look forward to more!

[Chris Jackson]

Mark...If your teeth are in good condition, ie; you have good engagement and minimal lash, you should be able to set the thrust such that you can crank easily with 1 finger and the wheel will coast down gradually. If for some reason yours is not moving in that fashion check the following:

-Gear Lash: Hold the hand crank still/rigid with one hand and attempt to rotate the grinding wheel clockwise and then counterclockwise with the other hand...how much play/lash do you feel in the gears? If it is more than a few thousandths each way you may want to seek out a different grinder to rebuild and/or locate a spare pinion...the pinion typically takes more of the wear as it is revolving at a faster RPM than the bull gear and therefore sees the majority of the wear.

-Thrust: Setup your hand crank on the bull gear shaft...get yourself some shim stock, a set of feeler gauges or a business card. Place 0.010" to 0.015" of shim (or a business card) between the side of your crank handle and the bull gear shaft housing...this will properly set the thrust on the bull gear. For the pinion gear, most hand cranks have a small adjustment screw on the shaft capture nut for the pinion. Put the pinion gear and wheel in place (it is important to have the wheel mounted to the shaft when performing this adjustment as the mass of the wheel determines the force required and the amount of momentum obtained) make up the nut finger tight until the pinion is as fully engaged as possible with finger tension (DO NOT REEF ON THIS WITH A WRENCH). From this position back the nut off in 1/4 turn increments tighetening the adjustment screw and capture nut, and giving the hand crank a turn to check opertion...if turning is stiff, rubbing or otherwise difficult, back off the pinion nut another increment until you obtain proper operation...

Hope that helps.

Cheers!
Chris

[Chris Jackson]

Installment #2:

Well, spent about an hour this morning turning down the oxide wheel to around 5" diameter. Truthfully it was 15 minutes to turn it down and 45 minutes to clean up the dust...it was everywhere!

**Note: Reducing a wheel from 6" to 5" with a diamond wheel dresser will wear out your diamond grit quite handily...looks like I'll be buying a new wheel dresser as well after this project is done!

Once that was done I got it installed and did a quick test to try it out. I'll be working on the base tonight, for now here's a couple of photos with the wheel installed.

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[Tony Shea]

Looks like a great grinder, one that seems to be hard to find these days unfortunatly. Have been looking for a similar one with not much luck. Turned out very well. Next step is your tool rest, and don't skimp this step as it is probably the most important. Which you may need to re-true your wheel in reference to your rest once you've got that installed.

[Mark Baldwin III]

Chris, that was probably a silly question on my part. It definitely seems that you know what you're talking about with gear trains, I should have picked that up on your initial post. I build gearboxes and such for a living, myself (ever picked apart a 300:1 planetary gear reduction? fun fun fun).
The roughness in mine came from the steel/steel contact on the crank. The thrust bearings, and a touch of endplay took care of that. I didn't go to quite the level you described because, well...it's a grinder:)
Tony-these things are out there to be found. I saw 3 of them on Saturday when I was out shopping. One as small as 2", a 4", and a 6".
Anyway, it's nice to see someone else doing this at the same time that I am. It'll be good to see another way of thought.

[Chris Jackson]

ever picked apart a 300:1 planetary gear reduction? fun fun fun).

Actually yes...a couple of transfer cases; a New Process NP205 and an Atlas II...used to be a big Jeep guy back in the days before wives and kids...

Glad to hear your into the wood projects as well.

[Mark Baldwin III]

I cut my teeth (pun intended) on electro-mechanical actuators. There is a position indicator drive in one of the ones I used to do that was about 1.5" in diameter and 1.5" long. It's a 3 level planetary, crazy little thing. Anyway, back to your grinder...Interested to see what you end up doing. I'm trying to think of the best way to set mine up. Will probably re-do my sharpening table as part of this.

[Dave Lehnert]

I saw a grinder just like that today in a retail shop. Passed it up because it did not have a tool rest. Wish I had seen this post 12 hours ago.

[Chris Jackson]

**Conclusion:

Well, took me a couple of days to wrap up...a few projects going around the house, lot's of "Honey Do's" slowing me down...

So, with the wheel diameter reduced and properly mounted I built a basic platform for the grinder.

This required a slight elevation to ensure that the tool rest would come in at an acceptable up angle. I accomplished this elevation with a couple of stacked pieces of plywood and a small mount platform. This also required a small cutout (see photos) for the thumbscew to pass thorugh the base, and I had to properly align this with the opening in my vise where I will work with the grinder most often...

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**Note...when you build your station, ensure that you understand where you will be mounting it, so that any clamping mechanism, and/or the crank handle do not interfere with your surroundings during use. Nothing worse than building the grinder base at your bench and then installing it where you are going to work and finding out you have some interference or other...

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So, that's it, I gave it a go on a fresh iron I picked up the other day, and within 2 to 3 minutes had a nice hollow grind. Now that I've tried it I really only have one or two surprises/concerns that I wasn't expecting:

-Wheel wear: The white oxide wheel seems to wear much faster than I expected, especially considering the slow speed...

-Wheel Availability: I am still not able to locate a 5"x1"x1"arbor wheel, and I'm not excited about the prospect of turning down another 6" wheel to a small enough diameter to use...


Hope someone finds this thread helpful...have fun!

Cheers!
Chris

[Jessica Pierce-LaRose]

I actually stumbled across a hand-crank grinder at an antique sale today; the wheel was about 2 1/2 inches across - it looked like it could maybe fit a 3 inch wheel max. The small size was actually kind of appealing (space is tight here) but assuming I could find wheels for that size, is this actually a usable size for our purposes? (That being chisels, plane blades, etc.)

[Dave Lehnert]

Thanks for the write-up.

Just FYI- The Shopsmith grinder attachment uses a 5" wheel. May be a source for replacement hand grinder wheel.
http://www.shopsmith.com/ownersite/catalog/sh_grindingwheels.htm