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-   -   Can you add a rheostat to a buffer? (http://forums.pelicanparts.com/off-topic-discussions/939169-can-you-add-rheostat-buffer.html)

Shaun @ Tru6 12-13-2016 04:23 PM

Can you add a rheostat to a buffer?
 
I have a bench top buffer that spins at 3600 RPM. I want to slow it way down to 500 to 2500 depending on what I'm doing. Can you wire one in that will slow the motor speed? Will it hurt the motor in any way?

Developed a new polishing technique that requires many different speeds.

http://forums.pelicanparts.com/uploa...1481678471.JPG


http://forums.pelicanparts.com/uploa...1481678471.JPG


http://forums.pelicanparts.com/uploa...1481678471.JPG


http://forums.pelicanparts.com/uploa...1481678471.JPG

stomachmonkey 12-13-2016 04:53 PM

Variac.

$50-60 on Amazon.

Or get a router table speed controller. HF has them for like $20.

Just plug it in and go.

Charles Freeborn 12-13-2016 04:59 PM

Depends on type of motor. If universal (with brushes), like a router or drill, yes. Induction, no. You can speed control an induction motor only if it's engineered to be variable speed.
What You Must Know About Motors - Popular Woodworking Magazine

rusnak 12-13-2016 05:02 PM

Like this? It might limit your top end speed, but if you need more speed maybe you can wire in a bypass.

<iframe width="560" height="315" src="https://www.youtube.com/embed/w1EsMwk2E5c" frameborder="0" allowfullscreen></iframe>

dad911 12-13-2016 05:06 PM

I believe that will reduce power considerably.

Can you use a smaller diameter wheel? That will reduce the surface speed at the edge of the wheel.

The 'porsche' mod would be a 3 phase motor with a VFD.

M.D. Holloway 12-13-2016 05:14 PM

swap out the gears...

Shaun @ Tru6 12-13-2016 05:28 PM

Quote:

Originally Posted by stomachmonkey (Post 9395582)
Variac.

$50-60 on Amazon.

Or get a router table speed controller. HF has them for like $20.

Just plug it in and go.

Thank you! Here's the spec plate (looks like 3450 RPM), which one do I need to get? It's a 1/2 hp motor.

https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=Variac

http://forums.pelicanparts.com/uploa...1481682293.JPG

Shaun @ Tru6 12-13-2016 05:31 PM

Quote:

Originally Posted by dad911 (Post 9395601)
I believe that will reduce power considerably.

Can you use a smaller diameter wheel? That will reduce the surface speed at the edge of the wheel.

The 'porsche' mod would be a 3 phase motor with a VFD.

The wheel size I use is important so I have to stay with that. What do you think of the Variac that Scott posted?

dad911 12-13-2016 05:43 PM

No experience with Variac, sorry.

id911T 12-13-2016 06:19 PM

Looks like an induction motor. The 3450rpm gives it away. You will need a single phase VFD to vary the speed. If the motor wasn't designed for a VFD, you will be limited on how much you can reduce the speed though.

stomachmonkey 12-13-2016 06:51 PM

It is a single phase motor.

Marked on the tag.

You are not going to slow that down easily or cheaply.

You'd be better off and probably save money by swapping for a 3 phase.

Charles Freeborn 12-13-2016 07:30 PM

Or swap it out for a 1725rpm motor. To run a 3 phase you have to have 3 phase power to your shop.
My buffer is belt drive so I can change speeds with different pulleys.

A variac will not work on yours.

M.D. Holloway 12-13-2016 07:52 PM

Used variacs in the lab all the time for stir bars and plates, hot plates, round bottom flask heaters. Used to hook them up to motors but all were 1725 if I recall.

Shaun @ Tru6 12-14-2016 02:30 AM

Quote:

Originally Posted by id911T (Post 9395699)
Looks like an induction motor. The 3450rpm gives it away. You will need a single phase VFD to vary the speed. If the motor wasn't designed for a VFD, you will be limited on how much you can reduce the speed though.

Quote:

Originally Posted by stomachmonkey (Post 9395730)
It is a single phase motor.

Marked on the tag.

You are not going to slow that down easily or cheaply.

You'd be better off and probably save money by swapping for a 3 phase.

Quote:

Originally Posted by Charles Freeborn (Post 9395767)
Or swap it out for a 1725rpm motor. To run a 3 phase you have to have 3 phase power to your shop.
My buffer is belt drive so I can change speeds with different pulleys.

A variac will not work on yours.

OK, thank you. I have 3 phase for the Cerakote oven but sounds like it's more trouble than it worth now.

1990C4S 12-14-2016 04:08 AM

Automationdirect has a lot of cheap VFD drives.

Their selection chart is here: https://cdn.automationdirect.com/static/specs/driveselection.pdf

javadog 12-14-2016 04:42 AM

Buy a used drill press that has belts you can reconfigure to change the speeds and use that as a buffer motor.

JR

Charles Freeborn 12-14-2016 05:34 AM

Guitar makers ( like me) use lower speed buffers with large diameter wheels (12" on mine). Grizzly tools has a good selection.

Shaun @ Tru6 12-14-2016 10:40 AM

For the short term I modified my new technique to use the high RPM.

Just did a test of a quarter window vertical, polished and then anodized.

Pretty close to chrome so I'm happy overall, but would like the safety of the lower RPM.

http://forums.pelicanparts.com/uploa...1481744361.JPG

Shaun @ Tru6 12-14-2016 10:41 AM

Quote:

Originally Posted by Charles Freeborn (Post 9395994)
Guitar makers ( like me) use lower speed buffers with large diameter wheels (12" on mine). Grizzly tools has a good selection.

I am limited to the size of the buffing wheels I use. A 12" one would be ideal but they are not available.

stomachmonkey 12-14-2016 10:46 AM

Quote:

Originally Posted by Shaun @ Tru6 (Post 9396429)
Pretty close to chrome so I'm happy overall, but would like the safety of the lower RPM.

I seem to recall you may have a handful of spare parts lying around.

Dig out some shafts and gears and build a transmission for it.

Use it in your marketing, "Polishing done by our one of a kind 915 Shinomatic"

Shaun @ Tru6 12-14-2016 11:30 AM

Yeah because re-framing my dentist's Ford Ranger, welding up a door pillar and kidney bowl on an 86, rebuilding the 928 engine, finishing the Cerakote oven, building a "proper" 2.7RS MFI motor, painting the Cabriolet and putting it all back together and creating the ultimate fresh salsa just doesn't keep me busy enough. :D

stomachmonkey 12-14-2016 11:43 AM

Pussy, you can sleep when you're dead.

Shaun @ Tru6 12-14-2016 12:20 PM

I can sleep when the salsa is ready. On version 12 now. I think 14-16 will do it, just have two variables to work out.

Decided to call it vivo.

stomachmonkey 12-14-2016 01:13 PM

Quote:

Originally Posted by Shaun @ Tru6 (Post 9396565)
I can sleep when the salsa is ready. On version 12 now. I think 14-16 will do it, just have two variables to work out.

Decided to call it vivo.

Mmmmm, salsa.

Eric Coffey 12-14-2016 02:57 PM

Quote:

Originally Posted by Shaun @ Tru6 (Post 9396565)
I can sleep when the salsa is ready. On version 12 now. I think 14-16 will do it, just have two variables to work out.

Decided to call it vivo.

Keep it somewhat P-car related: "Carrera Al baņo" :p

Shaun @ Tru6 12-14-2016 03:23 PM

???

http://forums.pelicanparts.com/uploa...1481761391.jpg

Eric Coffey 12-14-2016 10:04 PM

Yeah, Spanish is rusty-to-non-existent. Was going for "Race to the bathroom".

Carrera = "race"
al = "to the"
baņo = "bathroom"

I suppose it depends on how hot you are making the stuff. :D

Shaun @ Tru6 12-15-2016 03:05 AM

That's funny!

Charles Freeborn 12-15-2016 04:57 PM

Quote:

Originally Posted by Shaun @ Tru6 (Post 9396430)
I am limited to the size of the buffing wheels I use. A 12" one would be ideal but they are not available.

Grizzly.com

Shaun @ Tru6 12-15-2016 05:51 PM

Thanks! They don't have the type of wheel that I use for final buffing but I saw two others that I'd like to try and see what they do.


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