ID grinding hard chrome.

[Terry Keeley]

Is there a point where grinding it round, then lapping for size and finish makes sense?

It's got a very slight taper.

 

[Milland]

It's got a very slight taper.

Yeah, I remember that now. That's the issue with sporadic threads, you lose your place.

 

[michiganbuck]

French Canadians for sure, they are all craze.
We would never swim all the way to the point with not wearing any mittens.

I still would like a sketch of the wheel mount assembly right to and into the spindle. I could not find it on the internet. How much stock do you need to take?
Your part looks very good.
Buck

 

[Terry Keeley]

Ha! "Crazy Quebecois" we call them, I should know, I married one.

The collets that came with the grinder (I called NSK to order a couple more but passed at $80 ea!) have a 5mm stub, I made flanges to mount 1/4" hole wheels, the top one indexes on the stub so it all runs very true, I feel no vibration at 30K.







Think I got a good setup, it's no Heald or Parker Majestic but it seems to be working. I'm taking out about 0.005" per side.

Again, I'm really wondering about dressing the CBN wheels. I looked at my resin bond wheel when it was dull with a loupe and I could swear the grains looked rounded over, after dressing with the grit dresser and white stick they looked new and sharp. Am I just breaking out the dull grains and exposing new ones when I dress it? Again, any idea how to do the vitrified wheel? Anybody?

 

[EmGo]

Ha! "Crazy Quebecois" we call them, I should know, I married one.

Can't be any worse than china girls ...

I'm taking out about 0.005" per side.

That's actually kind of a lot for such a small hole. Doing 2" and 3" bores in carburized gears they'd usually clean up in about .003-.004" ) (total) then have a good .005" to get to size. Maybe drop back a little, or is the plating too erratic ?

About the photos, you carefully took them from an angle where we can't see but I hope you're using blotters, Mr Pilot Sir. Wheels without blotters is like coffee without cream and sugar, la zi ji without peppers, hamburgers without beef. It's just not right

 

[Terry Keeley]

Can't be any worse than china girls ...



That's actually kind of a lot for such a small hole. Doing 2" and 3" bores in carburized gears they'd usually clean up in about .003-.004" ) (total) then have a good .005" to get to size. Maybe drop back a little, or is the plating too erratic ?

About the photos, you carefully took them from an angle where we can't see but I hope you're using blotters, Mr Pilot Sir. Wheels without blotters is like coffee without cream and sugar, la zi ji without peppers, hamburgers without beef. It's just not right

Ha! I better not talk about the cute China dolls around here in case my wife sees this and I end up like John Bobbitt!

I had to get that much chrome put on to fill in the difference between the taper I'm grinding and the original so it comes out the same at the top (small end). Plating is good, I found a small shop that let me do the masking, in return for plating them I made them a couple other fixtures, good deal.












Yup, blotters are there, it'd be scary without them.

 

[triumph406]

Looking for a super-polish, thinking the 90 grit AO dry will work but we'll see.

On one of the Ukrainian FB model engine groups there's a video of the bore being polished with a white cloth wheel and compound, the end result being a mirror finsh bore. I presume the finish was very good post grinding, so not much chrome was required to be removed in the polishing

 

[michiganbuck]

Your quill looks pretty good. I would want the ID of the wheel hub closest to the wheel head to be a very tight (hand) fit to the quill nose diameter. I would likey use blotters on both sides of the wheel, and another blotter behind the wheel hub closest to the wheel head to ensure no steel-on-steel slipping.
I would solid-set my dresser diamond or grit dresser at .0005 from my finish ID size so I could safely rough the part too -.0005, so needing to play with only the last half thow., might spark-out at -.0005 and then go to finish size.
I would likely buy or have a grinding shop make a spare quill.
I would likely log my ID taper for a number of parts to see if a pattern existed so to play with my in-feed location and stroke stops to see if I could find the sweet spot that was best for size and straight..
I would likely set up a second machine with a hone so I might super finish, and straight finish size to .00005 when needed.
I would likely call Radic for wheel advice and try a white AO, pink AO, SC, CBN, and diamond wheel in that order.

Likely you are doing most/much of this stuff.

It sure looks like you have an excellent nitch business there.
Looks like Blind River, lake Matinenda will be making Ice next week, good.
Buck

 

[michiganbuck]

QT; oP: The collets that came with the grinder (I called NSK to order a couple more but passed at $80 ea!)
I was once offered a 3-state sales region from NSK for NSK inserts. At that time I think they had the very best ceramic inserts.

I wonder If Sam Beto is still with NSK? (not sure if I spelled his last name correctly.)

 

[Terry Keeley]

On one of the Ukrainian FB model engine groups there's a video of the bore being polished with a white cloth wheel and compound, the end result being a mirror finsh bore. I presume the finish was very good post grinding, so not much chrome was required to be removed in the polishing

Got a link? I tried searching but came up empty handed. Some of the best model engine stuff has come out of Ukraine and Russia over the years, sad the current situation. I've been messaging a buddy on FB that makes his own stuff with very limited resources, he was in Kherson but had to leave when the fighting got too bad.

Your quill looks pretty good. I would want the ID of the wheel hub closest to the wheel head to be a very tight (hand) fit to the quill nose diameter. I would likey use blotters on both sides of the wheel, and another blotter behind the wheel hub closest to the wheel head to ensure no steel-on-steel slipping.
I would solid-set my dresser diamond or grit dresser at .0005 from my finish ID size so I could safely rough the part too -.0005, so needing to play with only the last half thow., might spark-out at -.0005 and then go to finish size.
I would likely buy or have a grinding shop make a spare quill.
I would likely log my ID taper for a number of parts to see if a pattern existed so to play with my in-feed location and stroke stops to see if I could find the sweet spot that was best for size and straight..
I would likely set up a second machine with a hone so I might super finish, and straight finish size to .00005 when needed.
I would likely call Radic for wheel advice and try a white AO, pink AO, SC, CBN, and diamond wheel in that order.

Likely you are doing most/much of this stuff.

It sure looks like you have an excellent nitch business there.
Looks like Blind River, lake Matinenda will be making Ice next week, good.
Buck

QT; oP: The collets that came with the grinder (I called NSK to order a couple more but passed at $80 ea!)
I was once offered a 3-state sales region from NSK for NSK inserts. At that time I think they had the very best ceramic inserts.

I wonder If Sam Beto is still with NSK? (not sure if I spelled his last name correctly.)

Yu, "binderdundat" for most of that stuff, here's some of the wheels I've tried.



NSK deals mostly with dental stuff hence the big $$$, their industrial line (Planet grinders etc) has mostly gone be the wayside with modern CNC stuff. My little Falcon grinder was discontinued twenty years ago.

 

[michiganbuck]

Don't forget steel on steel is like skates on ice,the extra blotter may help

Gotta go..The Guys are waiting for a pizza.

 

[MCritchley]

Isn't Profi Ukrainian? I wonder how they are doing.

 

[triumph406]

Isn't Profi Ukrainian? I wonder how they are doing.

One of the Ukrainian engine builders has his shop in his basement, rumour has it the house above the basement is destroyed, but somehow the shop survived, not sure which one it was. Might have been the Fora factory

 

[triumph406]

Got a link? I tried searching but came up empty handed. Some of the best model engine stuff has come out of Ukraine and Russia over the years, sad the current situation. I've been messaging a buddy on FB that makes his own stuff with very limited resources, he was in Kherson but had to leave when the fighting got too bad.

Found this

https://www.facebook.com/video.php?v=726047697747808

on this FB group
https://www.facebook.com/groups/628149450658494/
Couldn't find the specific video of the cylinders being ploished, but I'm sure it was on this FB page)

There this

https://www.facebook.com/video.php?v=600774366941809

(ID grinding with wheel very close to id of cylinder)
on this FB page

https://www.facebook.com/groups/628149450658494/user/100010277533869/

also

EduardFacebook

www.facebook.com

 

[triumph406]

Do you want a super-polished finish or are the grinding grooves helpful for oil retention, like honing does ?

For the small diesel ic engines I think they use very highly ploished chrome plate steel cylinders with CI pistons. Some have found that pistons that are ground work better then lapped pistons, I'd assume then that the oil retention is on the piston rather then the cylinder. The finish on a ground piston is likely to be a little coarser then a lapped piston.

 

[Terry Keeley]

Isn't Profi Ukrainian? I wonder how they are doing

Yup, they make some of the best model racing engines in the world, not sure how they're doing now tho.

You want a mirror finish to reduce friction once it's run in, the sleeve has a very slight taper (typical is 3 thou per inch on the diameter) and the piston is made to start to seal about 0.100" from TDC. Piston material (high silicone) and the taper just below the crown are critical.

The marine racing motors I run are made by a small factory in Italy, unlike the aero guys that run 80% methanol and oil we run up to 80% nitro.

Thanks for the links triumph406, I can see they have way more rigidity with the large shanks and wheels, I'll get a Russian guy I know to have a look and see if he can tell me what he's using.

 

[EmGo]

Ha! I better not talk about the cute China dolls around here in case my wife sees this and I end up like John Bobbitt!

A really sad day in life is when they quit getting insanely jealous and just laugh at you - "You think you're gonna get that ? Try, I dare you !"

Your quill looks pretty good.

For once I sorta disagree with grinder buck ... if I can ever figger out this turbocad thing I'll have a project for you, flyboy.

 

[Terry Keeley]

This guy uses a home made "crush dresser" to true a diamond wheel, think it'd work for my vitrified CBN?

Starts at 9:24...

Same concept, no?

 

[Terry Keeley]

I finally got it, figured I'd add a final post to maybe help someone down the road.

Grinding hard chrome ain't for sissies, especially with a tool post grinder type setup. Everything has to be a rigid as possible including spindle bearings, sliding elements etc, if anything moves more than a tenth or two the wheel won't cut and will grab all of a sudden and pull into the work.

I tried resin and metal bond CBN but had the best luck with a Norton "Quantum" 60 grit wheel a buddy told me about. Final finishing was done with a Dumore 90 grit white AO wheel followed by diamond paste on a dowel. Sunnen MB-30 honing oil worked the best but was a mess so I settled on Rustlic WS-5050 soluble oil at 25%. How the wheel is dressed is critical, I tried cluster dressers and an old single point but when I got a new single point diamond made for the Quantum wheels things started to work. Infeed of about 0.002" per pass at a fairly quick traverse gave a sharp wheel..

Thanks again for all the help.

 

[Milland]

Good stuff, and thanks for the update!