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Lux mill to VFD

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Stuart Winsor12/10/2018 10:32:04
6 forum posts

Has anyone converted a Chester Lux (or similar) mill to VFD. I like my mill but sometimes I feel the ideal speed lies somewhere in between the available speeds. A VFD would seem to be the answer. I have seen a couple of RF45 conversions on the net but, for some reason I cannot fathom, they bypass the existing gearbox and use belt drive direct to the spindle.

To me it seems unnecessarily complicated, when all that is required is to replace the existing single phase motor with a suitable 3-phase motor and " bob's your uncle".

Can anyone point me in the direction of the correct motor to use?

Ian P12/10/2018 10:55:49
avatar
1936 forum posts
81 photos

Nothing whatsoever wrong in keeping the gearbox and changing only the motor. The end result will be a great improvement.

Given half a chance though, I would ditch (or just bypass) the gearbox and convert to belt drive. The resulting machine will be quieter and smoother and generally more pleasant to use.

In an already noisy environment its not going to matter but personally I find ventilation fans and even the hum from some transformers distracting. (I have converted my VFD fan to thermostatic control).

Ian P

John Rudd12/10/2018 11:36:21
1217 forum posts
57 photos

I'd suggest a 1.5 hp motor, to equal or better the existing motor. Frame size needs to match the existing, either 80 or 91...Your best bet is remove the motor and make a few measurements, shaft length and diameter for a start. Yours is a flange mount too, so that needs considering too.

Inverter wise, the Invertek series are pretty good ( I have two, one on my 626 mill the other on my big lathe..) The Invertek vfd has a thermo controlled fan too, so only comes on when needed...

My last package ( motor/vfd) came from Engineer's Mate....try google. Cost under £250...

not done it yet12/10/2018 12:37:57
2147 forum posts
11 photos

Ian P is probably right in suggesting retention of the gearbox (or at least some form of varying the speed mechanically). It can allow more torque to be transmitted to the spindle, and instead of running the motor slower while risking the reduced fan speed causing motor overheat.

Clive Foster12/10/2018 12:40:11
1465 forum posts
34 photos

Around 20 years ago I bought a Lux style mill from Chester factory fitted with VFD drive via a two speed belt system. No gear box as it was designed that way. I think motor was 2 HP. Seemed a good balance of speed range and power especially as there was a good overlap between high speed and low speed belt positions. Worst point was that changing belt was a bit of a struggle due to limited access.

VFD was a compact european built type without frequency display or control buttons fitted inside the head where gearbox is on the normal version. Neat way of doing things. I never missed the frequency display. Fitted a knob from RS with a numbered skirt running from 1 to 12 and stuck a number to speed conversion chart on the front face of the head. Used a stroboscope disk printed out from either ME, MEW or the internet for calibration. Strobe disk design from Tony Jeffee I think.

Were I to do one I'd use a poly Vee belt, reduce the speed range overlap to go a bit slower for facing / flycutting and put a bit more effort into belt tensioning system design to make belt shifting easier. Nothing intrinsically wrong with the set-up on the mill I bought. Usual simple eccentric motor mount with bolts running in curved slots. Just needed a bit more work on the details to make it easy to use with the head up in the air. As supplied would have been fine on the bench looking down on it but unnecessarily hard from below.

Mine was a one off to test the market. Price performance ratio clearly didn't work for most customers as being maybe 1/3 rd more expensive than the standard Lux. Perhaps £450 (ish) more in those days. Pity as I felt it to be a significantly better machine. Moved on to Bridgeport now which suits the work I do better.

Clive

Stuart Winsor12/10/2018 21:21:00
6 forum posts
Posted by John Rudd on 12/10/2018 11:36:21:

I'd suggest a 1.5 hp motor, to equal or better the existing motor. Frame size needs to match the existing, either 80 or 91...Your best bet is remove the motor and make a few measurements, shaft length and diameter for a start. Yours is a flange mount too, so that needs considering too.

Inverter wise, the Invertek series are pretty good ( I have two, one on my 626 mill the other on my big lathe..) The Invertek vfd has a thermo controlled fan too, so only comes on when needed...

My last package ( motor/vfd) came from Engineer's Mate....try google. Cost under £250...

I presume YC90-4L has some relavance to frame size. I've made a bookmark of engineers mate.

This is a possible project for the spring.

Thanks

Jon12/10/2018 22:10:38
874 forum posts
43 photos

I used to keep looking at mine, plenty of speeds available but just didnt spin fast enough 1250 rpm.

Face mounted motor and pulley would be inside the head!
Would need to make pulleys and adaptors to do so.

Junking the gears would get rid of a lot of weight plus the oil.

Without a spindle change, head modded for larger bearings these machines wont run a fast rpm.

Clive Foster12/10/2018 22:44:43
1465 forum posts
34 photos

Jon

As far as I know my factory VFD driven Lux style mill used same bearings as its gear driven brethren. Certainly the parts section of the manual covered both. Might have had higher speed capable bearings than the usual Lux style as standard of of course. No way of knowing.

Low speed range was 125 to 1400 rpm, high speed 250 to 2800 rpm. Left in low most of the time as that worked well enough. Coped just fine when I ran it fast in the high range but pretty sure I never went much over 2,000 rpm in actual use. Probably one went flat out once when I calibrated it.

Clive.

Jon14/10/2018 21:38:29
874 forum posts
43 photos

Fairly sure going back 12 or more years the max speed they could go to without problems was 2000rpm. There used to be a USA dealer modifying the castings to accept faster beefier bearings and modifying the spindle. Paid £900 for my Super Lux (ZAY7045L) sell off in 2004 recon everyone dismissed it as 3ph. Looked at it 8 yrs ago when replaced the inferior chinese bearings for SKF European. Parts are dear £244 for the elevation transfer box the motor sits on top. Really had it the last 5 years too much to put right.

Think i know the one you have Clive had my eye on one for a couple of years and substantially dearer. Has a two speed motor and the bearings have been uprated at factory. Theres a polish geeza on ebay selling them along with a couple of dealers over here.

Clive Foster14/10/2018 22:29:45
1465 forum posts
34 photos

Jon

Mine said White Eagle ZX32W on the front panel. Plenty of White Eagle brand machines on Alibaba with several iterations of the square column Lux style.

Current equivalent is probably ZAY7032 :- **LINK**. which appears to have similar two speed belt drive and VFD controlled 3 phase motor. Comes with auto-feed two which mine didn't have.  Bit surprised that no-one brings them into the UK as, if mine was typical, it would be a pretty good machine.  Lots of milling capability in a small space.

Says it comes with a 1.1 KW, 1 1/2 HP motor. Was sure mine was 2 HP but given that its been gone over 12 years I guess small memory lapses are acceptable.

Clive

Edited By Clive Foster on 14/10/2018 22:34:18

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