Tool Post Grinder

**rossbotics** · Apr 9, 2016, 01:55 PM

Thanks Steve
The belt I used was a jason flat belt 25.5", can be found at the link below, if the link doesn't work then just type in the search FLAT BELT it will take you the flat belt page there you will find the jason 25.5 belt
Jason 25.5M075 Flat Belt

Thanks
Doug

**sohackitj** · May 24, 2016, 08:36 PM

Great job! I have been thinking about a tool post grinder for my Myford lathe, and a design such as this is perfect. Nice Clausing lathe as well.

**ulav8r** · May 28, 2016, 07:08 AM

Originally Posted by rossbotics

I built this little grinder mainly for truing the jaws on my lathe and lathe centers, Maybe some light O.D. & I.D. grinding too.

The grinder has two interchangeable spindles, One for I.D. work which holds mounted stones with 1/4" shanks, The O.D. spindle supports up to a 4" O.D. tool post grinding wheel up to 1/2" wide.
The spindle is supported by two 5202 Double row shielded angular contact bearings rated at 10,000 RPM's. I machined 4 aluminum pulleys to accommodate the proper rpm's for I.D. & O.D. grinding. The I.D. spindle runs at 10,000 rpm while the O.D. spindle runs at 6,000. Changing spindles takes about 3 minutes.

The motor is a Dayton 1/2 HP 10,000 rpm, That I got off e-bay, The bearings were ordered from Mc Master-Carr, The flat belt came from vbeltsupply.com, The hardware came from local suppliers.

The grinder runs very smooth and relatively quiet, It did an excellent job on my lathe jaws, After they were ground I had a .0007" run out, Not to bad for a 3 jaw chuck.

Below are some photos and a couple links to you tube showing the grinder in use.

As always thanks for looking and happy machining

Doug

Attachment 7363

All the parts ready for assembly

Attachment 7364

External spindle installed

Attachment 7365

Internal spindle installed

External Grinding

Drawings would be nice to show how spindle is attached to the base and how the bearings are arranged. Internet Explorer will not show the embedded videos when I look at the thread, just a large blank area.

**owen moore** · Dec 11, 2017, 08:26 PM

That is a very nice and useful tool. If you fellows can't find that motor on Ebay, it can be had from W.W. Grainger Inc. I believe they also have a speed control for it if you want to spend the extra money. That motor is the perfect choice for that project. I have been thinking of putting one my old Dumore tool post grinder that needs to be rebuilt.

**petertha** · Jan 10, 2018, 01:52 PM

Very nice tool post grinder Rossbotics. I'm new to the forum but will grab a set of your plans. I really want to make a 'mini' version something along the lines of link for smaller, more finicky, sometimes angular work, but mounted on my 14x40 lathe. I bought a book on making spindles. I think I can make the various designs, but I still don't have a firm grasp of underlying principles of bearings selection. Some are plain & use anti-backlash adjusters, others use a spring, some call for angular contact bearings... It doesn't really elaborate on 'how much accuracy' or 'how long before heat issues' etc.

Can you describe the logic of what you chose & why. I cant quite tell by pics but do you have axial adjustment or compensation specific to the bearings?

two small grinding and milling spindels - Home Model Engine Machinist

https://www.amazon.ca/Spindles-Harpr...pindles+sandhu

**rossbotics** · Jan 11, 2018, 02:22 AM

Hi Petertha
Thanks for your comments, there are spindles you can buy, spindles normally have class 7 bearings and are called spindle bearings, and sold in matched pairs, those are quiet expensive, for no more grinding than I do the angular contact bearing in each end of the spindle works just fine, and yes it does have an adjusting nut to take out any end play, the angular contact bearing will take radial and axial loads, this is why I chose that particular bearing, If I were to be grinding on a daily basis say 6 hours a day then I would have went to the class 7 spindle bearings or better yet just purchased a spindle
According to the specs on the bearings I chose they are good for 10,000 RPM's, If you are going to be doing production work then I highly suggest you purchase a manufactured spindle.

Thank You For Your Inquiry

**petertha** · Jan 11, 2018, 01:14 PM

I bought your plans so will look them over closely. I got hold of a Themac last year & used it a bit (ID grinding cylinder liners for this 1/4sc model radial engine I'm building). Its a bit intimidating to me but doing the job. But for smaller things I was contemplating like valve shafts & seats or similar things at off angles, I'm finding the Themac a bit clunky to orientate, hence wondering out loud about constructing a homebrew 'mini' version.

Can you provide me guidance on the flat belt selection? Is that mostly a tangential speed thing, power related or certain length that this becomes critical? My Themac has very similar belt you are prescribing.

Also, would you consider it dangerous to orient the spindle at some angle, say 30-deg to lathe axis, but traversing in the same direction as bed with chamfered wheel? This mode would buy me some room around tailstock but now wheel is seeing some component of side load. I would envision max 1.5" dia wheel if that's helpful.

thanks again!

**rossbotics** · Jan 11, 2018, 11:52 PM

First off Thank You for purchasing my plans.

I purchased my belts from this company http://vbeltsupply.com I had a very hard time finding flat belts, you might say I built the grinder to match the belt instead of the other way around, my rule of thumb is to keep flat belts thin, narrow and short as possible due to vibration, also these braded belts are very strong, your not going to destroy them with fractional horsepower.

I have many times oriented my spindle at different angles to provide clearance, I don't think I would go over 30° though, it's possible you might create to much side pressure on the wheel and have a catastrophe like you say, and keep the wheel diameter small, say 2".

Just remember to keep the RPM's of the wheel to the manufacturers suggested speed.

Thank You
Doug

**ddickey** · Feb 14, 2018, 04:43 PM

Hi All,
I just finished the tool post grinder. I had a few challenges but got it finished, almost. I need to get the spacer block turned down some. Runs great. I hope to try it out in the next few weeks.