# Mini Lathe On-of Variable Speed Switch



## Ralphxyz (Jul 7, 2016)

I have a off brand Mini Lathe, the on-off variable speed switch is no longer working.

This switch is push pull for high or low speed, turn for on-off and vary speed so definitely not your average on-off switch.

Anybody have any idea where I might get a replacement?

Any body have a idea on what I might substitute?

On-Off I can handle, would just a radio shack potentiometer work.

I could have two on-off switches one for high speed the other for low if I can figure out the wiring.

I'll go back to the shop and get the Brand but I know it is not one of the common ones.  

Thanks for the help I am really going to need it on this one.


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## Billh50 (Jul 7, 2016)

I don't think I have ever seen a mini lathe with a switch like that. I would definitely like to know the brand.


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## Bob Korves (Jul 7, 2016)

You might want to ask Chris at Little Machine Shop.  He knows just about everything regarding mini lathes.
http://littlemachineshop.com/

Edit:  Welcome to the forum!


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## Ralphxyz (Jul 7, 2016)

It is a Cummins Variable Speed Mini Lathe!!


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## Ralphxyz (Jul 7, 2016)

Thanks Bob and Billh50, I sent Chris a note asking for his help!! 

I have never seen such a switch.

It was working on occassion, if I turned it just right it would work fine.
That was six months ago and I have not used it since.
Now I have moved it possible bouncing it a bit but nothing rough.

 I might take the switch out to see if there is any markings. 
I'll probable have to remove the fuse and emergency stop button first.


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## markba633csi (Jul 19, 2016)

It would help if you can post some pictures of the switch/pot and the controller board too.  Is there a schematic diagram anywhere?
MS


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## Ralphxyz (Jul 19, 2016)

I believe it is the same as the:
*Homier 03911 7x12 Mini Lathe*

*Micro-Mark 82500 7x12 Mini Lathe*

G8688 Grizzly 7x12 Mini Lathe




See the H/L 2500/1100 this is why I believe there is a push/pull speed control.
Just now I was trying to turn the lathe on and I actually bumped the motor for a second.

There is a note on the Homier site that one has to return the switch to 0 in order to turn the lathe on!!
That is my problem I cannot find 0. The switch turns 360°+, around and around.

The http://olduhfguy.com/ has a wiring diagram that might fit. I sent him a email asking if he could fix the controller
but have not heard back.


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## markba633csi (Jul 19, 2016)

Ralph check and see if the knob is just loose on the pot shaft. Is there a set screw that needs tightening? I also don't believe the "must turn to 0 to turn on" business, unless there is some kind of tricky mechanical latch on the pot inside. 
I believe your speed control board is a standard garden-variety scr controller which we here are all familiar with. 
Can you open up the electronics box and give us some more photos? 
Mark S.


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## markba633csi (Jul 19, 2016)

I stand corrected- there is an interlock which prevents the motor from starting unless the knob is turned to zero. Also you may have a mosfet type controller instead of an earlier scr type.  But first check the pot and knob.  I'm looking at the drive troubleshooting page on Little Machine Shop.  I shall return...
MS


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## Ralphxyz (Jul 20, 2016)

Bingo, markba633csi you da man!!!

At your suggestion to check the knob, if was loose on the shaft or loose set screw.
I inspected the knob and saw that the bottom edge looked that it was cracked a little.
I thought I would try to remove the knob so I started pry it with a screw driver.
The knob really resisted being pried and the knob started to break. Once it started to break I figured 
I would just go for it and kept applying more pressure. 

Finally the shaft broke!! The knob is held on with the most complicated collet method I have ever seen to just hold a knob on.
I was left with about 3/16" of the shaft left.
I got some small vice grips and fastened the to the shaft stub.
When I turned them I could hear a click, I had heard a click before but the motor had failed to turn except for that brief bump I accomplished 
yesterday. I also can not push or pull the shaft so I do not know about that.
So I plugged it in, making sure to hear the click turning it off first.
Voila!! I can turn my lathe on and off!!
Apparently the knob was spinning on the shaft, as using the vice grips it works as expected.
The motor really speeds up when I turn the shaft so I believe it is in the UP hi speed position.
I do not yet have a rpm counter so I only can say it turns fast and slow, BUT IT WORKS!!

Thanks again markba633csi,

Ralph


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## markba633csi (Jul 20, 2016)

(As he takes a humble bow) Great news Ralph! Now you can make a custom knob for it using the lathe 
Mark S.


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## Ralphxyz (Jul 20, 2016)

Actually I am going to send the control box to http://olduhfguy.com/. He says he should have a replacement
switch and he will go over all of the electronics.

I do not know how old this lathe is and I am sure it has a lot of hours on it knowing the prior owner.
So I think it will be worth it to replace the switch and get it checked out.


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## higgite (Jul 21, 2016)

Ralphxyz said:


> I believe it is the same as the:
> See the H/L 2500/1100 this is why I believe there is a push/pull speed control.



Ralph,

It is not a push-pull switch. It's just a common mini-lathe speed control potentiometer with on/off switch. The H/L markings on the faceplate are just an indication of speed range depending on whether you have the gear shift lever set on High or Low. See pages 17 and 18.
http://cdn0.grizzly.com/manuals/g8688_m.pdf

Hope this helps.

Tom


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## Ralphxyz (Jul 21, 2016)

Thank you Tom!! It was the H/L markings that were confusing me.


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## markba633csi (Jul 26, 2016)

Ralph why don't you just replace the pot yourself?  Bless the child who fixes his own, I always say. 
Mark S


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## Ralphxyz (Jul 26, 2016)

Pete is able to replace the switch and test the electronics and set what ever settings need to be set.

I sent him the controler, he has it repaired and is ready to send it back, it cost me a few bucks but it is all checked out.
Gives a confidence boost 

Besides I have so many things going on I do not have the time it would be possible this winter before I got around to 
taking the controler box apart and eventually putting it back together again.

The pot was working it was just the broken post on the switch that needed replacement, so the whole switch was replaced
and then the electronics recalibrated to match the new switch.

Ralph


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## Ralphxyz (Aug 7, 2016)

I have my controller back and it is working great.

It cost me $55.00 to have the electronics checked out, the switch replaced and the speed control calibrated.

I purchased the lathe for $100.00 so I think I am still ahead.

Pete at http://olduhfguy.com/ did the work, fast service.

I just cannot imagine having the time to replace the switch to say nothing of calibrating the speed.

My Clausing 8520 mill which I purchased at the same time has been in pieces for the last 9 months.

Hopefully I get to put it back together this winter.

Thanks everyone for your input and replies!!

Ralph


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## markba633csi (Aug 9, 2016)

You lucky guy- I want an 8520 or 30 too,  they go for a premium out here in Calif.
Mark S.


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## Ralphxyz (Aug 10, 2016)

I paid $500.00 for the 8520, this was from a friend/neighbor for the past 20 years.

He just got to old, so I took them off his hands so he would not have to try to deal with them.

I am looking at his South Bend lathe next.


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## markba633csi (Aug 11, 2016)

Might as well make it a matching set! Talk about right time right place LOL 
MS


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