Tooling Choices, identification & WM290 Feed Question

So the plot thickens and the errors found continue to grow in my change tables. Maybe. Read on.

Using Jasons method I've indicated my slide movements using the smallest incremental gear set of

45 75

|

80 20

|

H 85

With 10 turns of the chuck I get:

1.457mm with A

2.798mm with B

0.721mm with C

All as per the table give or take a few degrees of chuck start/end position variation.

However with the cross slide I get:

0.357mm with A

0.724mm with B

0.166mm with C.

OK C isn't shown on the table as it's deemed too small to be bothered with, but for A & B it is travelling twice as far as it ought to according to the table. Now this may be the way it's supposed to be - to do with the radius being half the diameter or something. Like I said I am learning all the way and happy to be educated, but surely the figures on the tables should be a linear distance and not a function of diameter etc?

If I'm not mistaken this will be yet another point to feedback to Warco.

Cheers

Dave

Well that is better than what the table shows and looks like your apron actually has a 4:1 difference between turning and facing feeds whereas mine is 3:1. which is a bit of apain to find a happy set of ratios without having to swap the gear train all the time. Would be interesting to see if Dave could measure his metric 280 and see what that gives.

As you say the feed rate on the lathe is amount tool moves per rev so remains constant irrispective of diameter or radius.

With the machine geared 45 80 20 85 (as per Dave B):

Actual Plate
C 0.015 0.03
A 0.03 0.06
B 0.06 0.12

Actual being half the Plate value makes the Plate consistent with the lathe's dial, which is graduated to show 'amount removed off diameter' rather than 'distance moved by cutter'. Dial graduation is six of one and half a dozen of the other. Being graduated in amount removed is convenient for most turning to diameter tasks, but is half the required value when cutting fins or threads to a depth. Graduating the dial in distance moved is great for threading and fins, but means mental arithmetic when turning to diameter. I don't think it matters.

I suggest to Dave B that Plate mistooks are low-priority, because right or wrong the plate doesn't matter much. What matters is the lathe's actual performance. Typos are just annoying. A missing gear from the change set would stop work entirely. Likewise, the gearbox refusing to change gear, smoking motor, refusenik speed control, fuses popping, electrical tingles, damaged ways, excessive run-out, bent lead-screw / half-nuts or wobbly bearings etc are immediate cause for concern! The best way to identify important problems is to use the lathe. I feel almost the worst thing a beginner can do is start with a deep inspection and measuring spree, especially if any of it involves dismantling the machine. It's too easy to get confused or misled. Better to use measurement to diagnose real problems rather than discover theoretical ones.

I recommend making several things. Start simple and move up. The more the lathe is used, the better it will be understood - good and bad. All lathes have shortcomings, quite often they're not important. If there are any show-stoppers, using the lathe should quickly flush them out.

Cutting metal will also show how good or bad the operator is! I've discovered I'm never going to win any competitions. By nature I'm an impatient bodger mostly making stuff for practical reasons. Truth is I lack the patience and attention to detail needed to do the best work. Love to blame my Chinese Lathe for ugly results, but the problem is mostly me. It's not the machine - I can make decently finished stuff simply by taking more care...

Once familiar with a machine, absolutely OK to pull it apart and make improvements.

Dave

Interesting view, but please do remember that within a few days of receiving the machine I tried cutting an 11 TPI thread and it failed which is where all the uncertainty with the accuracy of the tables emanated from. As a beginner I trusted the data provided and it didn't work. I don't feel that I should need to get a calculator out each and every time I want to select a particular pitch. That's what the tables are for surely?

It seems there is disagreement on the numbering on the cross slide tables as Jason says it is a linear distance - same as the Z Axis, but sillyoldduffer says it is a function of the radius being half the diameter thus moves twice as much etc.

After Jason's comment I reported this back to Warco and they have forwarded it to China. Didn't say whether it was right or wrong...? Maybe there is more than one convention?

I guess I'm a bit data driven. If I see something in a manual I expect it to be right especially on something that's been around for a while. Would have thought any bugs would have been sorted by now.

Turning is only a pastime for me. I get to play once or twice a week at best and then not for long. I guess Ill get better with time, but Id like to bottom out basic errors on the tool before I learn to adopt the mistakes and then relearn it after it gets corrected.

Though I haven't had anything on fire yet I have had a fault with a contactor that prevented the VFD from running at all. Big chunky contactors were never intended for switching 5v DC signals for fwd and rev but that's what is fitted and all it took was a little oxide on the contacts and my 1 day old lathe died. It oughta have had two small relays, one low voltage for the 5v signals and a separate one for the control switching which is all 240vac.

Again fed back to Warco. Whether they'll do anything about it is another matter. I'll mod it for reliability sake after warranty expiration.

Cheers,

Dave

No criticism intended! It's just a certain amount of pragmatism helps me get on with Far Eastern machines. And over the years I've been on the forum, a fair few chaps have got flustered due to starting with a theoretical examination of their new machine rather than successfully using it. I reckon faults that don't make a difference in the real world should be ignored! For example, your lathe can cut 11tpi despite the plate being wrong.

What should be expected of a hobby lathe costing less than 20% of its industrial equivalent is discussed endlessly on the forum. Some expect hobby machines to be just as good as professional machines, which I feel is unrealistic! On the other hand, what we have delivered into our workshops should certainly be better than a 'kit of parts', which was how too many of these machines were described when they first appeared. Although most of us get acceptable machines now, there are still occasional horror stories. They don't worry me much because the risk is low - bad examples can be exchanged for a better one or money back.

My experience with 6 Far Eastern machines is of finding minor issues only. Mostly due to rushed assembly and indifferent finish - nothing serious. Everything I bought worked out of the box with no fuss, but it all benefited from some gentle fettling.

For some, finding even minor issues on a brand-new item is unacceptable. And who am I to disagree? I just accepted inexpensive machines are likely to be a bit rough and did the necessary tweaking as faults emerged. No regrets, I've used a WM18 mill for 6 years and a WM280 lathe for 5 years with no issues, touch wood.

While they've both done what I want of them, I wouldn't claim they are the best machine tools in their class. In particular, I take care not to push the machines too hard, preferring them to sound moderately strained when cutting rather than laboured. Actually, I've never got the 1.5kW motor on the WM280 to warm up, despite taking deep fast cuts in carbide that cause an overly exciting spray of red-hot steel chips!

Re linear vs function confusion, I think that's just interpretation of words. I agree with Jason that the movement is linear in that it depends only on the gear settings and motor speed, and doesn't vary with distance from centre. Radius and diameter are a red-herring, I only meant the plate is consistent with the dial. In practice the plate doesn't matter much - apart from threading I leave the gears set for facing (45 80 20 85) and switch between C, A & B to suit the job. I've never actually used the plate for that purpose - eyeballing during the check phase is enough to show the tool moving too quickly. The plate might be useful as a guide to facing when gears happen to be set-up for threading; usually facing isn't advised with the gears selected for the coarse threads I usually cut.

By 'check phase', I mean the pre-flight checks taken after setting up and before applying a powered cut. Make sure the job revolves without hitting anything, the saddle and cross-slide are clear, the stop is positioned correctly, slides locked or unlocked as appropriate, forward/reverse, gears, interlocks, and other controls engaged correctly, and any other sanity checks. For example, after changing gears on the banjo I always double-check the resulting pitch by running the tool point by hand sufficient to scratch a few spirals. It's because I get the banjo wrong 1 in 6 attempts by misreading my notes or misplacing the gears. Shameful but true...

Dave

Edited By SillyOldDuffer on 05/03/2020 17:30:35

Dave B, I was wondering the same thing the other day as to why they have a 20amp contactor for switching 5 volt 10ma.

There is 240 volt feed wire conected to 43 on the contactor is for a built in fan on the back end of the three phase motor, this is switched via the forward /off /reverse (10 - 9) switch and is not using the contactor to switch, I was geting a lot of EMI swiching noise when switching from reverse to off so I rewired the fan control wire from 43 to a separate switch,

On my Warco 280VF the VFD is switched on and off via the E stop switch.

I put a diagram in my Album (Not figured out yet how to show it here)

I ditched the change gears for the clough42 ELS project, I can now cut metric / TPI threads at the press of a button or two, and I change turning feed rates on the fly.

YouTube

The circuit diagram in the manual is fairly representative of what’s actually there but there are errors. The fan connections were something I found to be slightly different. There’s also no filter as described, but I think that refers to the psu for the rpm counter.

what they really need to do is add a small low voltage psu (there’s actually already one for the rpm display so just make it bigger) and make all the control low voltage. The drive can be reconfigured to take 24v inputs rather than sink it’s own 5v supply signals to ground. Then do away with the contractor and replace it with a small relay as the vfd handles all the high current, this would still not comply with modern machinery safety standards unless the drive had a safe off function but even that is doable. Small low voltage relayed scrub their contacts as the contacts land. Slight sideways movement. Part of the design. Contractors do not. They land square. With higher voltages and currents this isn’t an issue, but with low voltage it is as the contacts do not “clean themselves” during operation. I will be modding mine after warranty.

I’ll also wire the fans so they only run when the drive does. It’s the only time heat is made inside the box and anything more is just annoying unnecessary noise.

The lead screw mod is very attractive, but I gotta get past warranty and be sure turning is for me before I do anything radical.