Mini Lathe On-of Variable Speed Switch

Ralphxyz

Ralphxyz

Registered
Registered
Joined
Jun 17, 2016
Messages
18
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.
 
I don't think I have ever seen a mini lathe with a switch like that. I would definitely like to know the brand.
 
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.
 
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
 
I believe it is the same as the:
Homier 03911 7x12 Mini Lathe

Micro-Mark 82500 7x12 Mini Lathe

G8688 Grizzly 7x12 Mini Lathe

Controls.jpg

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.
 
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.
 
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
 
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
 
You must log in or register to reply here.
Back
Top