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Mini Lathe
Status Broken - need to fix or replace the motor
Origin ???
Location Machinery wall of Unit 23 (near Equipment/LaserCutter)
Maintainers mentar,Billy Smith,booyaa
[[image::File:None.pngBroken - need to fix or replace the motor???[[location::Machinery wall of Unit 23 (near Equipment/LaserCutter)]][[maintainers::mentar,Billy Smith,booyaa]]

Mini Lathe

The mini-lathe is an example of a widely copied 7x12 lathe that has been manufactured in several versions

See also Equipment/LatheMillCombo for the bigger mill / lathe


?minilathe Status: Not working. Low torque, and causes ciruit breaker to trigger on high revs.


Update 13/03/2013

aaron (& mentar): Checked the brushes -- they are wearing on one side, and there is some play in them tangentially to the commutator. Mentar and I ground some new ones to be a bit closer fit. But the commutator will need cleaning up before we use the motor again, otherwise it will wreck the brushes. Please do NOT use emery paper to do this -- it can wreck the motor! Also, I think I've figured out the main reason why it's not working! Details to follow, in case I'm completely wrong :)

Update 09/03/2013

aaron: Took apart all the mechanics (with the exception of the spindle itself), cleaned/re-oiled everything, and put it back together. The leadscrew mechanism was quite stiff, but rotates a lot more freely now. I had to very slightly file down the edge of one of cog shafts, which seemed to have flared out a bit and was sticking. I've left it covered by a tarp, with the motor removed.

The motor itself still has the problem of tripping the circuit breaker (it hasn't magically healed itself), and at low revs has a very noticable sparking around the commutator. Apparently there are lots of ways to mess up a motor when trying to clean it, so we should be careful. I found some potentially very useful information and have put it into Equipment/MotorMaintenance.

Update 07/02/2013

mentar: Put it back together. Paddy tested the lathe and it is still misbhehaving, at high revs it trips the circuit breakers. New motor costs £120 from china.

Update 02/02/2013

aaron: I've taken apart the motor and did my best to clean it out. There was a setscrew loose inside there, but it was pretty well stuck to the one of the magnets. It appears to be used to secure the gear to the shaft. Also, I am guessing that there might be a problem with carbon dust building up between the contacts of the commutator, which could possibly cause a short that would make the motor draw a lot of current (though this would not likely cause a ground fault). I've cleaned those out as well. I haven't done any testing yet though.

Update 11/12/2012

mentar: The lathe is still misbhehaving, at high revs it occasionaly trips the circuit breakers. The torque is pretty low. Lathe debugging is complicated by it being on the same ring as the laser cutter so can't be worked on if laser cutter is in use.

Update 27/11/2012

mentar: Needs service. One of the brushes broke away from the connector, this has now been fixed, the lathe ran without problems for a few minutes. Needs a thorough clean and service

Update 01/11/2012

mentar: Almost working, but don't use yet! The control board need tuning to make sure it supplies the right amount of current to the motor. Found the ACCEL pot placed in a position which the manual specifically says IT SHOULDN'T BE PLACED IN (at the minimum setting). My guess is someone "tweaked" the values, hence the problems. Will read through the manual fully and tune it, hopefully next week. I should note that during one of the test runs the lathe tripped the 3A fuses (which according to the manual limit the motor to a 1/3 HP). I've replaced with a 10A fuse on the plug and a 7A fuse on the control panel (so the motor will go to a max of just under 1 HP)

Update 09/10/2012

mentar: Brushes replaced with the help of Charlie, motor running well without load but when connected to the drive belt spins very slowly. And it's almost like there is some sort of current limiting. Need someone with knowledge of control electronics to take a look.

Update 02/10/2012

mentar: Coils fine, commutator covered in a beefy layer of carbon, one brush almost gone. Replaced the brush with a smaller one from a one of the motors in the "motors" box, cleaned the carbon residue off the commutator and it works, sort off. The speed controller only works for a small range and the speed is constant after about 20%, this could of-course be due to a brush that wasn't meant for it. I'd still advice people against using it just yet, but if someone who has seen it working before the fault can take a look and confirm that it's not behaving properly that would be great.

Update 05/09/2012

Billy has offered to fit the brushes if someone orders the brushes. Expressed concern about the off-centering of the armature, which will probably require the motor to be replaced in the future.