New member, Lagun Mill

[Smokie555]

Hi guys, great forum. I’ve done a bit of 3D printing and drawing but I’m new to CNC. I have been playing with Mach 3 demo for a while and now plan to convert my LAGUN FU-1 LA Mill to CNC using one of those £350 eBay kits with Nema 34 1600oz steppers. My machine has really good tight beds but some backlash on the lead screws with 0.008” on the X , 0.0001” Y and 0.004” on the Z. I can adjust the X down to 0.005” but with a noticeable stiffening on the hand wheel. Being a knee mill the Z moves the entire bed and therefore takes 9.5 lbs feet torque to get moving up but the X & Y are below 1 lb ft to start moving, so can I use say Nema 23’s 1200 on the X&Y with a 34 on the Z?

Can you mix motors sizes on one break out board with different drivers and power supplies?

Has anyone converted a Lagun machine?

So many questions, am a wasting my time with these eBay jobs? http://www.ebay.co.uk/itm/1517158967...%3AMEBIDX%3AIT

It’s for hobby use only and my main interest is motorbike parts etc so it only gets infrequent light use.

[Robin Hewitt]

Stepper motors should be chosen by looking at graphs showing torque against speed. You can mix and match. They are all 200 steps/rev which suits 2.3" a lot more than it suits 3.4". The stepper market is dedicated to American's who believe more is better and need to be told what to do and what to buy because that is how they were taught in school. Why do you want to power the bed vertically when you can power the quill? You can put a screw along side it. Fix that backlash first or it haunt you.

[komatias]

The lagun is a universal mill right?

You would be better served with servos and good quality ballscrews. Way too much weight to push around and up/down.

Not what I would call an easy conversion by any standard.

[Smokie555]

Ahh, stepper 23 & 34 case size = inches. I have read that over sizing the motors apart from being bulkier and more expensive, results in a slower machine? I thought the speed would remain regardless of size.
Unfortunately my universal mill has a fixed head and therefore no moving quill as per pic’s. My measurement of 9.5 lbs feet of torque to move the Z axis is around 1800 oz in, of course I need to be able to plunge and cut etc so with 2:1 gear reduction I thought I would be ok. But with the X & Y requiring a fraction of the torque to move the tables I maybe need to look at 2.3” steppers for these.
I take your point that backlash is a problem that won’t go away but I am reluctant to start into a ball screw conversion until I’m confident I can get the CNC stuff working. Where do the UK people on the forum buy their hardware from?

Sorry for the daft questions and thanks for the advice

[njhussey]

Its not just the moving the table the steppers have to deal with its the cutting force as well, plus the acceleration of the mass and stopping it...I'd have thought that servos would be best but 8 & 12Nm Nema 34 steppers coupled with 230V drives should see you right.

Don't be tempted with kits of electronics, they're seldom well matched. Zapp Automation, CNC4YOU are good for steppers etc.

What's the all important budget?

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[Smokie555]

Thanks guys, I'll check out CNC4YOU and stop being temped by the cheap kits on ebay. Neil, I'd be happy to spend around £700-800 if I was going to end up with something that works well but if not I'd maybe do better selling my current machine and putting it all towards a different more suitable Mill.

[Neale]

There are quite few Bridgeport conversions around. Might be worth having a search for some of those to look at what other people have done with a similar size machine?

[njhussey]

Thanks guys, I'll check out CNC4YOU and stop being temped by the cheap kits on ebay. Neil, I'd be happy to spend around £700-800 if I was going to end up with something that works well but if not I'd maybe do better selling my current machine and putting it all towards a different more suitable Mill.

What size items are you looking to machine? This will help make your mind up regarding converting your mill or buying another. Your mill wont be the easiest to convert as you have to motorise the knee rather than the quill. I'd say that £700 - £800 will get you decent steppers and drives and a motion control card, you'll need to spend nearly the same again on cable, relays, control cabinet and general bits and bobs, its amazing how it all adds up!

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[Smokie555]

Despite it being a good sized machine I normally only cut alloy and even then its mostly light plate etc but its always nice to have the extra capacity for when its needed. I'm not so worried about the extra's as we never include them in good projects in case the wife see's the bills but I agree that these can easily double the outlay. I was considering grafting one of those alloy Z axis from CNC4YOU and using a high speed cutter to avoid my knee moving problem but it’s hard to give up the rock solid ridgity of the current machine plus the use of all my 30 INT tooling. I'm going to drop into my local used machinery dealer and see what he's got anything more suitable for a swop deal. Thanks again for the replies.

[njhussey]

Or make your own Z axis from Ali tooling plate to bolt on where the current head goes and use a 2.2kW spindle for cutting Ali, then you've got the original for steel. Would be a bit of a pain having to set up every time but I guess depends on how much you'd use the 2.2kW compared with the original?