Yes I love my old roundhead. Obviously I would rather a DSG or a Holbrook. The only real problem I have is too slow a top speed. 1000rpm not enough.
- Thread starter Hood
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Hood
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I very rarely go above 1000rpm, the drawback to a lot of other lathes for me is spindle bore, that is where Colchesters are decent.
Munkul
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I'd love to see how you did this - is there a thread on it somewhere?
Hood
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There is now
Motor mounted to a plate behind the headstock.
Plate from end of headstock showing belt/pulleys.
Box with a power supply and some switches, labeled as to function.
Switches to control the servo.
Off position is no switches.
Normal spindle rotation is lower switch.
Reverse spindle is upper switch.
Munkul
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How can I use the phrases both "ugly and dirty" and "simple and elegant" in the same sentence?
It's a cleaner and easier installation than I'd thought... does the servo give you some motor braking? And what's your high and low speeds? Clearly works well enough to justify spending some cash on it!
Most folk would have thought "knackered headstock... that's that then" lol
It's a cleaner and easier installation than I'd thought... does the servo give you some motor braking? And what's your high and low speeds? Clearly works well enough to justify spending some cash on it!
Most folk would have thought "knackered headstock... that's that then" lol
mtt.tr
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no different than how most cnc machine spindles are drivenHow can I use the phrases both "ugly and dirty" and "simple and elegant" in the same sentence?
It's a cleaner and easier installation than I'd thought... does the servo give you some motor braking? And what's your high and low speeds? Clearly works well enough to justify spending some cash on it!
Most folk would have thought "knackered headstock... that's that then" lol
Little baby lathes usually have an open belt drive and a back gear.
I don't know why Colchester used all geared heads - far more expensive to make. And a belt drive gives higher speeds and better finish.
Then again VFDs weren't around in those days and nobody used carbide tooling.
Munkul
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It'll just be spinning the gears back to the clutch and input drive shaft, and making a racket since it's worn out. Looks like he took the belt pulley off and left the shaft.
I know this is how most modern CNC lathes are driven etc, I was just impressed at how simple a solution it was to bypassing the gears
Hood
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Aye was done in a rush about 10-15 years ago, had just got the lathe and of course the smart guy I bought it from had it in a barn with no power so couldn't be tested, typical farmerHow can I use the phrases both "ugly and dirty" and "simple and elegant" in the same sentence?
It's a cleaner and easier installation than I'd thought... does the servo give you some motor braking? And what's your high and low speeds? Clearly works well enough to justify spending some cash on it!
Most folk would have thought "knackered headstock... that's that then" lol
I spent a whole week turning some nylon pulleys for a friend to help him out as he was stacked out with work, I had to use ear muffs to stop getting a splitting headache. So once I had finished that job I said F it and grafted on the servo in a day.
Hood
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Aye as said I am just bypassing the gears between the spindle and original motor/clutch. I have the gears disengaged via the levers as if they are engaged they get back driven from the spindle.
The gearing after the spindle for feeds etc are still used so I can still do everything that is needed on a lathe such as threading, power feeding etc.
Hood
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Yes servo brakes the motor, I have a braking resistor in there to help. High speed I think I kept at 2000, low speed is as low as you want
I didn't spend anything on it really, already had bought the servo drive and motor from eBay for projects, prob cost under £100 for them, belts and pulleys were probably more expensive.
Brad93
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That’s dc is it or AC?Yes servo brakes the motor, I have a braking resistor in there to help. High speed I think I kept at 2000, low speed is as low as you want
Hood
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AC
Hood
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Yes and although I keep promising to replace the motor with a smaller one it is currently and likely always will be, getting driven from the original 7Hp one
Brad93
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Like that a lot. Dead quiet now!
Munkul
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Oh I see... Of course it is, why fix what aint brokeYes and although I keep promising to replace the motor with a smaller one it is currently and likely always will be, getting driven from the original 7Hp one
That servo brake setup works a treat!
I've spied another M400 short bed on facebook with headstock problems... advertised clutch issues but probably a dropped gear set reading between the lines... almost tempted to buy it and do a similar conversion... for no other reason than because I really like the idea! I'd probably struggle to find a s/h servo and drive setup quite as nice as yours though.
Hood
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I had a 12Kw servo on the CNC lathe but kept blowing drives so had to put it back the way it was originally.
Shame as it was brilliant via the servo, seems there is a weakness about the Allen Bradley HV DSD servo drives, I have had a few fail on different machines, the standard voltage ones seem to be good but sadly they only go to 3kW.
I have an older DDM style on the Triumph, it is 240v 3 phase and seems to have stood the test of time, it is 7.5Kw drive.
Shame as it was brilliant via the servo, seems there is a weakness about the Allen Bradley HV DSD servo drives, I have had a few fail on different machines, the standard voltage ones seem to be good but sadly they only go to 3kW.
I have an older DDM style on the Triumph, it is 240v 3 phase and seems to have stood the test of time, it is 7.5Kw drive.
