# Tool Post Grinders



## Big Bore Builder (Apr 12, 2012)

I have posted this on another site, but might be interesting for those that have not seen the photos.


Handy things to have: Made in the shop. Both have DC motors and I have a variable speed controller for power.








Motor pulley is twice the diameter as the spindle pulley. Both are flanged. The flat belt is a vacuum cleaner belt.





Spindle has a double sealed ball bearing on each end. Guard is from a 4 inch side grinder. Grinding wheels are standard tool post grinder wheels, rated for high RPM. Motor is from a 1/2" drill minus the gearbox. 5000 max. rpm, variable speed DC. I use a diamond point to dress the wheels. I also have chucks to fit the threaded spindle allowing the use of grinding points.








Big flanges are the order.








The central bolt screws into a slide that goes in the compound rest T-slot.







The Belt Grinder








The central slotted bar is a sliding tensioner. Spring on the back side. The two small wheels have internal ball bearings and are hard rubber contact wheels. Motor pulley is flanged.







The hex bar is bored for the shaft and has two locking set screws, allowing rotation of the grinder to either contact wheel grind or slack belt grind. The nuts are just props to position for the photo.





A good view of the tension spring.







I will put up more photos in a hour or so showing the belt grinder in use.


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## Tom Griffin (Apr 12, 2012)

Thanks for posting the pics. There is a toolpost grinder on my to-do list. I want to make it so I can grind ID's as well as OD's so there is some engineering to be done. Using a DC motor is a great idea since it's a lot easier to control the rpm of a DC over an AC motor.

Tom


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## pdentrem (Apr 12, 2012)

Well there is an other one for the to do list!


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## Big Bore Builder (Apr 12, 2012)

TLGriff said:


> Thanks for posting the pics. There is a toolpost grinder on my to-do list. I want to make it so I can grind ID's as well as OD's so there is some engineering to be done. Using a DC motor is a great idea since it's a lot easier to control the rpm of a DC over an AC motor.
> 
> Tom



Just turn the knob to control the speed!


The grinding wheels I use are standard tool post grinder type rated for high RPM.   Don't use cheap wheels!!!!!  Don't forget the guard!!!!!

I have small  die grinder type chucks to replace the grinding wheel, allows me to use small grinding points.

Once you have a tool post grinder the first thing you will do is grind all the lathe centers true.


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## Big Bore Builder (Apr 12, 2012)

I purchase the banded type front sight ramps on the small side, then fit using a combination of grinding the muzzle and reaming the inside of the band with a sanding type reamer. With the belt grinder I can blend the ground area nicely back to the barrel diameter.   Note the grinder is tilted back with the contact wheel against the barrel for a uniform grind.










End result is a nice fit for silver soldering:
















Below I am polishing the barrel with the grinder tilted for “slack belt” opereation. Here I am running the grinder in reverse (against barrel rotation), so the dust plume goes upward and is sucked up by the vacuum.





The belt grinder also works great when blending muzzle brakes:


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## bcall2043 (Apr 12, 2012)

Big Bore Builder said:


> ......... Note the grinder is tilted back with the contact wheel against the barrel for a uniform grind.




Thanks, Big Bore

The belt grinder is a neat design. 

Have you tried to hold close dimensions with the belt grinder contact wheel against the part? If so what were the results?


Benny


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## Big Bore Builder (May 12, 2012)

More:

Tool Post Grinder Belt Drive.

I need to make up another set of pulleys, with the large on the spindle and small on the motor. With the 3-1/4" wheel shown, the spindle is now too fast with motor at max RPM, I run it at about 1/3 speed. Belt is a flat vacuum cleaner belt, it does not jump off like a V belt or round belt.

Pulleys are crowned and have flanges.


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