Suggestions for Craftex 7x8 with Speed Control issues

Glasswalker

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So I am looking at the Craftex 7x8 lathe. I want something small and benchtop, I don't plan on doing anything requiring extreme precision, I also don't plan on doing any large parts outside that envelope. Finally right now I simply don't have the budget. I'd rather spend some money now, find out if I can use the machine to the point of hitting it's limitations, and if I then find I can justify it, move up to higher cost.

I did machine shop in highschool, and worked with metal lathes there. But it's been a LONG time... I'll be essentially re-learning all the basics. So once I get it operational, then I'll be trying out some basic skills, and learning a lot, so I'll be asking lots of questions on the forum in general lol... But for now I want to focus on getting the lathe into top shape (for an asian import small lathe of course)

Anyway, I dicovered this lathe: http://modelengines.info/lathes/craftex.html at a local used shop tools store... They usually refurbish, and re-waranty used gear, and provide some support and so-on... I stop on the way to visit family regularly.

I stopped in and they had the Craftex 7x8 lathe in, and had it marked "as-is" on clearance... The owner explained that the speed control is "flaky" and they don't touch electronics at all... He powered it up and fully demonstrated it. Mechanically it seems perfectly clean, and everything works well. It just has flaky speed control. Specifically, to me it looks like a bad potentiometer in the controller. (ie: as you turn it up, it cuts in, cuts out, sometimes alternates from high to low speed, and at certain positions on the POT it runs consistantly at a speed). It occasionally crackles and snaps as well... I was also thinking it could be a bad brush in the motor... Will be hard to tell until I get my hands on it and crack that controller open...

I'm an electronics engineer, so ultimately even if I have to replace the entire motor, and control system with a fresh one I'm comfortable with that, but ideally I'd love to stick to minor repairs for now.

Good news it's $300 as-is, and looks immaculate. The owner explained that a regular customer who build model steam engines used it for about a year or so, and decided to scale up when the motor started flaking out. He brought it in and they thought they would fix it but decided to sell as-is once they realized it was an electronics problem.

So I'm going to snag it. I'm accepting it as a project. That said any suggestions:
A) any suggestions for the speed control issue (from those perhaps familiar with this machine)
B) Anyone have an electrical diagram for this machine?
C) Any other suggestions of things to check/do/clean/inspect/calibrate/tune/upgrade?

Once I get it operational and smoothed out. Another thing I'd like to be able to do is get started milling with a milling attachment. Anyone have any thoughts on that for this lathe?

Finally any other feedback? :)

Thanks!
 
I would suggest offering them much less. The 7x10-12 lathes often go for $200 or so used in functional condition. Another thought is the work envelope of my 7x12 is pretty small. I would not go any smaller for any reason. Good luck! I forgot to mention, parts availability and accessories are plentiful for all the 7x10-12-14 lathes. Check out Little Machine Shop. They have tons of tooling, replacement parts, and upgrades. They even sell some machines. I doubt the different design has anywhere near the availability of these things.
 
These lathes had a few production years and progressive control board changes.
I had the potentiometer go on mine ( The same B1979c Craftex.)

I got a 4.7
potentiometer from Ebay actually I got 3 for $10. easy to fix. they may not ramp the same as the original .

Just make sure you get a Linear pot, NOT a Audio pot.
 
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