[How-To] Harig Grind All #1 Disassembly and adjustment

[kenpo11]

Greetings fellow hobbyists..First time posting and I thought I would start a question and answer session on a new project I'm working on. I just acquired a Harig Grind All #1. Upon inspection, I checked the runout and manually pressing on the V-block, I could get a movement of .005+..Not good. Also the fine adjustment screw for the V-block was missing and 3 teeth on the V-block for adjusting were broken. I have dissasembled, cleaned and inspected all the componets. Slight wear line on the center of the races from ball bearings. No physical or indicatable wear on the races..only slight visable bearing track line. I will attach a few pics of the project. Objective is to tighten this back to "reasonable" tolerances. Factory specs I hear is to within .0001 I will not be worrying about achieving that. Being I'm shooting in the dark here, I am looking for an option on tightening it up. My first notion is to grind the Back side of the bearing plate. The main housing has the races for the 32 bearings ground into the center of the body. No way to revive them. The front part which consists of the V-block is a 2 piece design. It is bolted from the back with (3) 10-32 screws which Sandwich it together on the bearings on the internal races. My thinking is if I grind the "back" half an undetermined amount, that will compress the bearings together to remove slop in them. Question is...How much? I was kicking idea around of starting with .0005, reasembling, testing it and working upwards from there. I can grind the rear portion easily but....it's going to be a feel it process. I would appreciate any suggestions. I have heard some people describe the races in these consisting of 2 washers ground and placed together to form a 90° for the bearings and that is what decides the preload. This has nothing like that. The 2 halves are "Tightened" together...No preload. Attached pics..

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[Aukai]

Welcome

 

[kenpo11]

Much appreciated, Thank you

 

[Cadillac]

What’s the variance in ball measurement? I’d probably measure and replace the balls first. Regrinding the race would be a challenge. As you know these tools should be sub tenths.

 

[kenpo11]

Appreciate the reply. I measured and inspected each of the balls. They ALL measured .2861.
I had thought there might be some wear amoung them but they all are exact. Don't have the manual or specs on the bearings but would guess since they all measure the same, should be good. I mentioned 3 of the V-block teeth are broken and the fine adjustment screw is missing. I have one on order from Harig.
Possible someone Crashed the unit and damaged something? Everything appears intact with nothing showing severe abuse. The design puts the Outer race as made into the housing. The front (V-block) section and rear (gear handle) portion bolt together to comprise the Inner race.
Bearings are cheap. I will due elimination process (head scratching) before I attemp anything Drastic. Thanks for the suggestion.

 

[kenpo11]

As be it my last reply..I typoed a wrong input. The measurements of ALL the bearings are identical at .2811. I corrected from last post of .2861. Found info on the dia of bearings and they are factory of .2811 as I measured mine at. Appears no wear on bearings.

 

[kenpo11]

At this point I have disassembled it 3 times. Mic'd everything and checked for warpage, alignment and still scratching the head. Placing the balls in Dry and rotating it will allow the V-block face to "move" ever so slightly back and forth if you even "Pinch" the V-block face and housing. Mic'd and it is out .005 doing this. I did realize that the preload is weak to non-existant as the bearings will move freely without any strain. I've experimented with the preload and have concluded the "inner race" needs to be compressed therefore raising the bearings higher onto the "Outer race" to create the preload. I am going to grind .0005 off the back plate which im hoping will moderatly raise the bearings on the inner race and present some preload. This should allow the inner race to move together to cause the slope of the race to raise the bearings. All surfaces and races seem to be in pristine condition. Stay tuned..

 

[kenpo11]

I'm back...
Interesting food for thought for anyone finding themselves in a situation like mine. I disassembled the unit again.. I placed the Back inner race plate on the Harig 612 and guestimated how much I should remove. My guess started at .0005 of removal.
Upon reassembly my guess was close. After checking error, it came within .0009 ...Started out at .005. Going to press my luck one more time. Going to go .0002 and hopefully don't over shoot the runway.
Problem is still a mystery how this could have happened. Haven't found the cause for needing to grind the back half of the race.
Stay tuned..

 

[dkemppai]

Problem is still a mystery how this could have happened. Haven't found the cause for needing to grind the back half of the race.
Stay tuned..

Probably way off base here, but just curious... If it doesn't look like it was crashed is it possible it's a knockoff? Spent some time looking for a harig, and abandoned that idea eventually. But I don't recall seeing any in green?

 

[kenpo11]

Good point....I'm no expert and this is my first experience with one of these. The plate on top is a Harig plate. Pic attached.
It appears factory and of good quality but now...Hummmm?
Thanks for that...you just added another thin spot to my scalp..LOL
Thank you..