How Do I Mount This Trimmer To This Bench Grinder?

3400 rpm is kind of fast.
But a thread adapter would do it, assuming one with the correct thread pitch for both can be found.

Oops, one needs a set screw, thought they were both threaded.

Do you have a speed controller?

Looks like you need a 5/8 inch to 3/8 inch rigid adapter. Something like this...but with the bore diameters that you need... (the link is for a 1/2 inch to 3/8 inch)

https://www.amazon.com/Climax-CC-05...gid+Couplings+5/8+x+3/8&qid=1616542601&sr=8-6

Using a heavy grinding wheel or even a heavy piece of steel on the opposite end will slow the speed down a bit.

Cutting brass usually happens at much slower speeds. I'm not going to say is a bad idea but I would contact the manufacturer for a maximum rpm. They will likely be quite surprised at your speed range. I would say your most likely exceeding the design specifications of that tool.

I couldn’t find much of anything I would want to spin up to even a thousand RPM. Something like what @peels has, but a 5/8x11 threaded on the arbor side. Maybe just a clamp on would work, but I’d rather have it threaded on.

peeplwtchr said:

Thanks. So the true search name for this type of device is a Clamping Coupling?

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Yeah. Thats the typical name for it. You can tell I tried to search for 5/8 x 3/8 in the link...but didn't get any hits. You may be able to order a 5/8 to 1/2 and then use a shaft bushing to step up from 3/8 to 1/2. Not ideal, but I think for brass trimming, it should be ok.

https://www.amazon.com/Amana-RB-122...ft+sleeve&qid=1616553759&s=industrial&sr=1-45

I took an old battery drill that ran on 12 volts and secured it to a base with 2 big hose clamps. Mounted my trimmer and adjusted the speed by a zip tie on the trigger. Powered from an old battery charger with a switch in line. That grinder looks nice though.

That right side would be the side to use, the other end is likely left hand threads. I would bore a piece of steel so it is a good fit to the shoulder of the shaft and tap it deeper so it runs as true as possible, then counter bore for the attachment and drill and tap for a set screw.

Wouldn’t it be easier to just mount the trimmer in a drill press ... ?

Of course, you must have a drill press to do so. Just thinking you are taking 1/2 of the grinder’s usefulness away if you mount the trimmer on it in fixed fashion as you describe.
I have my similar case trimmer mounted in my drill press and it’s a matter of 5 seconds to remove if I want to drill something.

But, a grinder mounted trimmer as you describe would certainly work and be convenient.

drband said:

Wouldn’t it be easier to just mount the trimmer in a drill press ... ?

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Absolutely but that wasn’t the question.

A little bench top drill press would be a good choice, especially if he would have to pay someone to machine an adapter for him. That might cost more than the drill press.

jmorris said:

Absolutely but that wasn’t the question.

A little bench top drill press would be a good choice, especially if he would have to pay someone to machine an adapter for him. That might cost more than the drill press.

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My drill press is my case prep center where all the attachments go. Trimming, pocket uniforming chamfer, debur and anything else I need.

AJC1 said:

My drill press is my case prep center where all the attachments go. Trimming, pocket uniforming chamfer, debur and anything else I need.

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Can you provide a picture? I would have thought that looking down at the press would make it inefficient to use?

I just clamp my electric drill in a bench vice and use the trimmer like that. Drill is variable speed with a lock trigger.

1. When heavy objects spin fast they become dangerous to the user. That is, they can fly off the motor and the user could be struck and seriously hurt.

When I attached my son's Giraud Tri Way cutter to his 1725 RPM motor, I used a non-flexible Rigid Shaft Coupling. These clamp the cutter securely to the un-threaded motor shaft AND maintain concentricity, which is required to maintain system balance. The threaded shaft end will NOT maintain concentricty, which will lead to extreme vibration (from imbalance) and the danger of flying off.

These Rigid Shaft Couplings are available from McMaster-Carr, Grainger, and many other industrial supply houses. I happened to find a new old stock (NOS) item on Ebay for a fraction of it's list price.

Most Shaft Couplings are flexible and these will ABSOLUTELY not work. CLICK HERE and scan down the page to the clamp on Rigid Couplings section.

2. To further limit my son's danger, I wired up a simple foot operated power switch. This sits on the floor under the trimmer. When the trimmer is needed, he places his foot on the switch and trims the cases. When his foot is removed, the motor returns to the OFF condition and the risk is again zero. These type foot switches are sold on Amazon. CLICK HERE

Hope this helps.

One option is to get yourself something like this,
https://www.ebay.com/itm/Replacemen...d-Drill-Chuck-for-Electric-Drill/283990973231
you will have to know the arbor size, one search I did said it was 5/8

Just4FunOldGuns said:

One option is to get yourself something like this,
https://www.ebay.com/itm/Replacemen...d-Drill-Chuck-for-Electric-Drill/283990973231
you will have to know the arbor size, one search I did said it was 5/8

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In order to fit a drill chuck, your shaft would require BOTH the 1/2-20UNF thread AND the correct alignment shaft diameter. In a drill chuck, the threads do the holding and the shaft does the alignment.

Since the motor spins at 3400 RPM (2X the recommended), the concentricty specs of the chuck would be important to know.