Mini Lathe lost drive

Dear Model engineers,

I was working at parting off some 63mm dia aluminium bar this afternoon when taking a light cut it just stopped.

I switched off to let it cool, I didn't feel hot nor had I been working the machine hard.

Switching on I thought i heard the no volt relay pull in, this was confirmed by lifting the chuck guard and i could hear a relay drop out.

The speed display lights and spinning the chuck by hand gives an rpm reading. The chuck feels unusually free spinning.

I checked the belts which are intact

so i guess its a problems with a fuse or the drive or motor.

I am reasonably competent with electrics and electronics but before I start pulling the thing apart to find the fault I wondered if anyone had any advice/experience of this happening to them?

The lathe is a Amadeal AMAT 210V with a brushless motor drive.

Many thanks  Paul McD

Edited By Paul McDonough on 11/08/2023 17:23:17

Well, I found two fuse holders on the rear of the machine and one, a 5A fuse had blown so i am off to replace it to see if it was simply a blown fuse due to the heat/me working it without sufficent breaks or if something else more serious has caused it to blow. fingers crossed!

Well it was the fuse, as replacing it with a similarly rated 5A fuse allowed me to carry on working, however I managed to blow this one a short time later. I now see that the replacement fuse i have a a fast blow, so it looks like I'll have to order some slow blow fuses as per the original.

I hope that this is the issue.

Sounds like you hit lucky there, Paul

MichaelG.

I have never been a fan of the replace a blown fuse and keep fingers crossed strategy.

In your case, two fuses have blown. You have a problem. Find it and fix it!

.

Only the first should need worrying about, Chris … the second was a fast blow.

Edit: __ or did I read it wrong ?

MichaelG.

Edited By Michael Gilligan on 11/08/2023 19:53:25

I got a load of 5A fuses from ebay and have burned through quite a lot on an old AEI motor for my Drummond

If the fuses are doing their job then it's all good, 5 minutes or less and off you go

At the startup when it sucks a lot of juice seems to be the biggest cause of stress

Edited By Ady1 on 11/08/2023 20:05:27

Somehow, I doubt you are fitting the correct fuse. The fuse is to protect the supply lead, nothing more.

Yes the only fuse I have ‘in stock’ are fast blow, it didn’t surprise me when it didn’t take much working. I have ordered some 5A slow blow from RS Components which should arrive today. If this fails I shall look further.

that is assuming that the correct fuse was fitted to the lathe in the first place, as it’s secondhand.

Edited By Paul McDonough on 12/08/2023 08:01:41

Hugh at Amadeal ought to be able to tell you what is the correct fuse, and supply replacements.

If not, talk to Ian at Arc Euro, to see if they can supply the correct fuse.

Give him full details of the lathe, so that he will be able to find the right part.

But if the correct fuses blow something is wrong, or you are asking too much of the machine.

Remember it has a relatively low powered motor, in a hobby machine, and running at low speed means little air flow to cool the motor. Hopefully, you have not already done damage.

What speed?

What depth of cut?

What feed rate?

Howard

Thanks Howard,

Thanks for your good ideas. I will check the manual to see if it lists the fuses as ‘parts’ otherwise I’ll drop amadeal a note.

I think you may be right about me working the machine a bit hard, it’s just that I am used to a Unimat 3 and that really has to be treated with kid gloves.

it is quite hot in my work shop (shed) too so that probably doesn’t help.

the fact that it is still working is a blessing, if it forces me to upgrade the motor and drive so be it.

Have you checked the motor by itself - disconnected from the lathe gearbox - for free turning? A motor bearing might have failed or be dragging for whatever reason, e.g. dust ingress, causing too much current to be drawn for the turning speed you want.

.

Edited By John Doe 2 on 12/08/2023 10:35:28