[digits]

Hi guys, as the title says, has anyone done a belt-drive conversion of this type of mill?

I have already eaten 2 sets of spindle gears, and just blown my spindle motor, and so am really quite keen to convert it to a nice quite belt drive and VFD/Induction motor. I'm not really looking for a higher top rpm, as my mill is still manual.

Unlike the smaller BF20/G0704 there are no obvious splines at the top of the spindle to attach a pulley to, and I'd quite like to keep the quill operation.

Any pointers would be much appreciated.

Ta.

[arizonavideo]

You do have splines they just dont stick out the top. I think Hoss is working on a belt drive but If you need it now I would think it is up to you.

You have a big bearing in the top of the head that holds the final drive gear and it has the splines in it. You would have to remove it and machine it to hold a pulley and then add a new motor. You might be able to find a motor with a long output shaft that might let you just use two pulleys.

You did not say exactly which machine you have?

[digits]

Thanks - I'm looking at the exploded diagram in the manual and I can see what you mean now (though this manual is a bit dodgy as it has the column from the WMD20 in it )

I have the Warco WM18 version of this mill. Overall I'm pretty happy with it, but my impatience and it's ability to take rather meaty cuts most of the time have caused me to get rather over aggressive with the DOC - hence my self inflicted spindle failures!

[Kipper]

Has anyone dug around the inside of one Digits?

Is yours the long table version?

[digits]

Has anyone dug around the inside of one Digits?

Is yours the long table version?

Hi Kipper - yes mine's the long table version. 830 odd mm of table, giving me ~575mm of X-travel.

I'm half tempted to disassemble the spindle myself, but I've put my back out and the head has got to be 40kg+

I have ordered a new DC motor but I'd still like a belt conversion - I can't believe how quiet my belt-driven drill-press is compared to the gears in my mill at the same unloaded rpm. It is a simple v-groove belt though - my DIY X3 spindle with HTD belt was far from silent.

[Kipper]

Get the back fixed and strip and measure it all...Then take a look at multi-vee belts for some inspiration.

Get well soon matey! :cheers:

[digits]

Get the back fixed and strip and measure it all...Then take a look at multi-vee belts for some inspiration.

Get well soon matey! :cheers:

Cheers Kipper - this is very tedious, and I wasn't even lifting anything when I injured myself. Hmm, how hard is a CNC exoskeleton?

[digits]

Well, I've finally got my new motor connected up and I've tuned the current limit back to about 5.2A which is what the manual claims is the motor's rating.

The KBIC manual I used for tuning the drive strongly recommends a fuse on the motor armature lines - I think I'm going to add circuit breaker, and I'm also tempted to add an ammeter as a spindle load meter. I'm pretty sure I overheated my motor during over ambitious cuts before it finally gave up the ghost once I started messing with the current limit. The problem with the mill is that it's just so capable - and manual milling is a whole lot less tedious if you can take fewer, deeper cuts!

I think I'm also going to move the motor-control box off the mill's head - I don't think that's the best place for it.

[digits]

Well, I finally plucked up the courage to take my WM18's spindle apart:



The splines are ususally covered by that black tube on the left which also covers the rather beefy quill-return spring.

The base of that double gear contains an inner spline which drives the spindle:


I'm not sure I could cut an internal spline like that so I guess the best bet is to try and attach a pulley to the top of the gear itself -



though not much more than 10mm of it sticks up above that upper bearing.
I'd guess I'd need to mill a flat or keyway into it to get enough torque through to the spindle. Looks like you might need a working mill to work on this mill!

[SCzEngrgGroup]

If you want to attach a pulley to the gear, bore the pulley to several thou under the OD of the gear end, then cool the gear and heat the pulley. They'll slip together easily, and be locked together for life. I'd recommend putting a lip on gear, to make sure the pulley seats square to the axis of the spindle. If you want some insurance, after it's assembled, drill an axial hole at the gear/pulley interface, and put a dowel or roll pin in it, to act as a key. It'll never move on you.

Regards,
Ray L.

[digits]

If you want to attach a pulley to the gear, bore the pulley to several thou under the OD of the gear end, then cool the gear and heat the pulley. They'll slip together easily, and be locked together for life. I'd recommend putting a lip on gear, to make sure the pulley seats square to the axis of the spindle. If you want some insurance, after it's assembled, drill an axial hole at the gear/pulley interface, and put a dowel or roll pin in it, to act as a key. It'll never move on you.

Regards,
Ray L.

That is an excellent idea, but I think I'd probably want to be able to remove the pulley - I'm not likely to get it right first time!

The drilled pins for drive are a great and much simpler idea than a milled keyway - I could do them on a drill press, or even by hand if I made a jig. What's better, axial pins, or radial setscrews?

[eartaker]

Couldn't you cut the splines you need with a rotary broach on a lathe?

[hoss2006]

Wow, I wish the G0704 had as much meat above the bearing, we've only got about 3mm.
Could have just milled 4 flats on the spindle and used setscrews to hold a pulley
in place.
Hoss

[digits]

Wow, I wish the G0704 had as much meat above the bearing, we've only got about 3mm.
Could have just milled 4 flats on the spindle and used setscrews to hold a pulley
in place.
Hoss

Cheers Hoss - sounds like a plan!

I'm not going to do the conversion immediately - I need the mill running for an urgent job. Just got a replacement for the quill bearing I broke taking those pictures, so it's time to put it all back together.

[brauta]

Some months have passed since the last posts....and I am starting to plan my belt-drive conversion of a mill (bought from Amadeal), the XJ-25, which I think is in the same family as the WMD30/WM18/Opti-BF30.

Any news?

[digits]

Some months have passed since the last posts....and I am starting to plan my belt-drive conversion of a mill (bought from Amadeal), the XJ-25, which I think is in the same family as the WMD30/WM18/Opti-BF30.

Any news?

I've not made any progress on this myself - too many other projects on the go unfortunately. I might have another go once the CNC conversion is done.

One of my main reasons for wanting to convert it - apart from the fragility and expense of those plastic gears is the noise level, but IMHO the main source of noise is the motor. Perhaps it might be worth an upgrade to a VFD + induction motor in the future...

[digits]

OK, so perhaps it's time to fire up this thread again as I've just killed another plastic gear

I've just measured the motor and spindle shafts. Motor seems to be 14mm diamter, and the spindle shaft 55mm with 15 odd mm visible above the bearing (with the speed-sensor disc removed).

I think the smallest taper-lock bushing that'll take 55mm is a 2517 - and I think that'll mean well over 100mm/4" for the spindle pulley - probably not an issue with the stock motor as we want to gear that down, but it might be an issue with an induction motor with a 1400rpm speed...

[digits]

I measured the stock motor RPM with my laser-tacho tonight - it reckons 2740 odd, and a spindle speed (in high gear) of ~1970 rpm. Unless it's way out, I guess I must have lowered my max spindle-speed pot when I was playing with the motor driver.

Anyway, that means I only really need a 2:1 reduction ratio in the belt drive to match the low-range gear, which is the one I use the most, and the one which I keep destroying!

I think a 64-tooth on the spindle and a 22 on the motor might be a good first guess, for a max-speed of 1000 rpm odd with plenty of torque.

[digits]

Well, I did read the dimensions before I ordered the pulleys, but I must have been in denial - I didn't realise quite how massive the 64-tooth one was until the parcel I was expecting in a small padded envelope turned up in a big heavy box. I can see why it was so expensive now!



- That pulley is over 150mm/6" in diameter and weighs several kilos, look at the size of the keyway, this is designed to take a huge amount of power!



There is just about enough room to get the motor on there as well, without fouling the rotating head mechanism.

The motor pulley is a much more sensible size, but only wide enough for a 20mm belt:



I really like these taper-lock pulleys, I think I might use them on my motors and ballscrews in my CNC conversion of this machine.

[hoss2006]

wow that's big, is it just clamped to your spindle flange or id you add a keyway?
definitely heavy duty looking and better than the plastic gears by far.
Hoss