# Colchester Bantam



## doubleboost (Mar 14, 2009)

Hi
I have not posted foe some time but i have been watching
I have just bought a new lathe (new to me)
The lathe is 3 phase i am open to advice on 3 phase converters
After a clean up we noticed some damaged teeth on the rack .I was going to weld up the damaged areas and file them back to shape.
After talking to a old machinist he came up with a safer solution ,the damaged teeth were milled away and 2 5mm cap head bolts locktight ed in to place.
After some filing the results are very satisfactory.






















Regards
John


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## Tin Falcon (Mar 14, 2009)

John talking to folks on the subject If I were in your shoes I would be checking out a VFD from Automation direct. You should be able to find what you need for around $100 for a 3 hp model. 
Tin


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## kvom (Mar 15, 2009)

I have an AutomationDirect GS2 VFD for my mill, and it has worked well. You do lose HP as the frequency and speed are reduced, so for very low speeds back gear is needed to maintain torque.

You do need to know that a VFD is not tolerant of load shutoff, so you should not use the lathe's power off switch to stop the motor when it's turning. If this is a problem then a rotary phase converter may be a better fit. That may also be the case if the lathe's gearbox is sufficient to supply the spindle speeds that you want from a constant speed motor.


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## Ian B (Jun 11, 2009)

John,

Good method of repairing damage.

The last time I saw / did this, was on my HND Mech Eng course. I spent 2 six month periods at Fenners in Hull (the vee belt mob). The maintenance department regularly received a cast iron pinion from the rubber works, about 3 feet diameter, 3 feet wide with teeth about 4" high. Every so often, an entire tooth would break off.

We ground the area flat, drilled & tapped a row of about 1 1/2" Whit holes, screwed in a 4" long steel pins. The whole lot was then arc welded up and ground to shape. By now, the pinion probably has a full set of false teeth - my dentist would be proud of it!

Regards,

Ian


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