Milling on a Combi Lathe/mill

[richardandtracyParticipant @richardandtracy]

[richardandtracyParticipant @richardandtracy]

I have had my Warco WMT300 since 2002, and as I expected a majority of my work has been using it as a lathe. I now want to do a bit of milling and have experienced a few problems with the machine moving under cutting loads.

I wonder if anyone with a combi lathe mill can give me any advice. The sort of combi machines similar to my Warco are the Clarke CL500M, Chester Model B, etc – there were many re-badged versions.

The areas I am most concerned about at the moment are the direction of milling on the machine. What direction did you mill in? If I lock the cross slide and the use the cross slide feed, I know the table won't move along the bed, but the milling head occasionally pivots, meaning I can't mill a straight line. To avoid the head pivoting, the answer seems to unlock the cross slide and move to towards the headstock. If I do this, even with tight gib strips, the cross slide seems to wander from side to side according to the cross slide feed nut backlash. Should the gibs be tightened to make the cross slide immobile when milling towards the headstock?

Finally, how did you measure the down feed on the quill? The graduations are 0.042" on my machine, I want to measure to 0.05mm, and the fine feed knob gives 101.5 times that for every turn, but has no graduations. At the moment I've not worked out a usable measurement procedure that's quick enough.

Now, I realise these are basic questions, but I want to get the sorted before I do much more milling – I'm working on a dummy part at the moment while I get it sorted.

Regards

Richard.

 

Edited By richardandtracy on 11/03/2018 22:06:11

[Clive FosterParticipant @clivefoster55965]

This is from discussion, advice and conversation rather than personal experience but I'm convinced the below is good:-

1) Downfeed measurement :- Fit one of the inexpensive read-head on a stick devices.

2) Wandering slides :- Lock all but the slide you are moving. Normal procedure for all small mills anyway, along with larger machines doing anything other than the lightest of work. Add thumb lever operated pusher screws close to the middle of the gib so you can easily lock things up. Some versions already have one or even two such on the slides. Verify that the feed nuts on the slides are firmly attached. Such tings have been known to work loose.

Don't whatever you do futz about with the gib screws. Takes a fair bit of time, effort and fettling to get the slides working at their best. When you have it right you want it to stay right.

3) Wandering head :- All you can reasonably easily do is to arrange some form of steady bar fixed to a strongpoint. Inevitably it will be bit Heath Robinson and some creativity will be needed to permit height adjustment but it will make considerable difference.

Theoretically the best answer would be to somehow bolt the milling head in place but that won't be easy. Certainly not if you want neat. Possibly two reasonably hefty plates fixed to the side of the headstock extending upwards to clamp the milling head might be possible. Slots could be provided for the bolts on either headstock or milling head so it could be moved up and down.

As you know it is inevitably a machine seriously compromised by design so light cuts will always be the order of the day when milling. Objectively the height adjustment capability on the milling head is probably a compromise too far for most work. Some versions have it bolted down solidly as standard.

Last I heard the person most concerned reckoned he'd got it to being a decent co-ordinante drilling machine but milling still needed considerable care.

Clive.

[richardandtracyParticipant @richardandtracy]

Clive,

Thanks for your reply. Made me think a bit, and make myself wonder why on earth I didn't think of a backstop for the milling head to stop it being pushed sideways, possibly with a boltable clamp to hold the machine in position. That is a really sensible idea, the wall of the workshop has several railway sleepers as the main uprights which should be stiff enough and capable of being bolted into.

I was looking at the cross slide yesterday & thought it might be good to have a thumb screw to lock the cross slide. With you re-inforcing the suggestion, it's something I'm going to do. Having a wandering table with the face mill I was using is not much of a problem, but if I were using an end mill, that'd be it: wrecked tool & work.

The vertical quill extension measurement. Hmm. Given how often I have used the milling head, buying a dro or similar is probably not cost effective. But, clamping a flat plate around the end of the quill for a dial indicator to press against while it remains attached to the main part of the head is a good idea. I shall see if I can adapt my normal dial indicator holder to do the job.

I'm aware the machine is a compromise, but it was originally bought to go in a yacht I was planning to build, so I could have on-board repair facilities & there was no room to have 2 separate machines. Since my circumstances changed, and the yacht idea abandoned, I have been unable to justify having a separate mill. My first serious need for milling (apart from making a few small taps) is 16 years after getting the machine, so it was probably the right decision.

Regards,

Richard.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by richardandtracy on 11/03/2018 22:04:13:

Finally, how did you measure the down feed on the quill? The graduations are 0.042" on my machine, I want to measure to 0.05mm, and the fine feed knob gives 101.5 times that for every turn, but has no graduations. At the moment I've not worked out a usable measurement procedure that's quick enough.

.

A quick & dirty solution might be to attach a disk to the fine feed knob, with 203 divisions.

MichaelG.

.

See fig 10

https://www.clarkeservice.co.uk/manuals/metal_lathes/cl430_500m.pdf

Edited By Michael Gilligan on 12/03/2018 09:04:56

[Neil WyattModerator @neilwyatt]

Or use a cheap digital caliper as a DRO, it will do the job well enough for occasional use.

[richardandtracyParticipant @richardandtracy]

Michael,

That guard on the CL500 is not the same as my machine (which clamped around the black ring at the bottom of the quill), but uses a feature that is present on my machine. I will investigate, thanks for pointing it out. It will make attaching a measuring device easier. It's amazing how often you look at things without really seeing them…

Neil,

A cheap calliper may work, especially if it's one of the older type that never switches off. However, how do you ensure that the one you're looking at is that type? The more modern ones turn off completely & don't spring back to life when you move them. They save the battery by doing so, but loose the old setting.

Regards,

Richard.

[richardandtracyParticipant @richardandtracy]

Eureka

Just remembered I have a horrible vernier calliper that cost me peanuts. I lost the locking screw off my daily use one and bought a cheap one to replace/donate parts. The cheap one was so horrible I didn't want to use it. Could be attached to the machine permanently and have a real use. And I wouldn't have to feel it graunch as un-finished surfaces slid over one another.

Regards,

Richard.

[Neil WyattModerator @neilwyatt]

You could also wire in an external AA battery holderm, which would last years.

N.

[Howard LewisParticipant @howardlewis46836]

Another thought, regarding cutting loads; IF it needs to be said, avoid climb milling. Any flexibility in the machine will allow the cutter to be pulled into the work.

As already said, the milling function has to be light duty, relying on pretty minimal clamping.

Howard

[richardandtracyParticipant @richardandtracy]

I played about with the location from MichaelG and attached bracketry to allow a cheap & nasty vernier calliper to be attached. I used the idea of the depth measuring rod to attach to the quill, but had to replace the stainless rod that came with the calliper with a longer 3x1mm carbon fibre rod bonded in with epoxy. Both ends of the calliper can be moved to re-set the zero where necessary.

The fixture is as below:

No permanent mods to the machine were necessary, and everything is reversible.

I attached a gib clamp lever on the cross slide through a ready tapped hole in the side of the saddle, obviously put there by Warco for that purpose without ever mentioning it in the handbook. The cross slide dial is set up for diameter turning, and it's an effort to remember that the movement is half what the dial says.

Did my first real milling over the weekend (made 5 Tee Nuts – wow, so complicated!) and now can claim I'm starting to be a beginner. It was much easier with the cross slide clamp & the quill scale than it ever was before. Thanks for your advice. At some point I will fit a prop behind the milling head to prevent it rotating about the lathe headstock & improve the stiffness further.

Regards,

Richard.

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