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Smokie555
28-09-2016, 12:31 AM
Hi guys, great forum. Ive done a bit of 3D printing and drawing but Im 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 23s 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/151715896714?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

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

Robin Hewitt
28-09-2016, 12:10 PM
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
28-09-2016, 05:22 PM
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
28-09-2016, 06:59 PM
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 advice1935519356

njhussey
28-09-2016, 08:06 PM
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?

Sent from my HUAWEI VNS-L31 using Tapatalk

Smokie555
29-09-2016, 01:07 AM
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
29-09-2016, 08:55 AM
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
29-09-2016, 09:03 AM
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!

Sent from my HUAWEI VNS-L31 using Tapatalk

Smokie555
29-09-2016, 01:54 PM
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
29-09-2016, 02:18 PM
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?

Smokie555
29-09-2016, 04:46 PM
That might be the best route Neil, I must search he forum and see if anyone else has made one to copy. You said about using 230v drivers for the steppers, I assumed they were all 230v input? with lower voltage outputs in the 24-80 v range, is that correct?

njhussey
29-09-2016, 07:57 PM
That might be the best route Neil, I must search he forum and see if anyone else has made one to copy. You said about using 230v drivers for the steppers, I assumed they were all 230v input? with lower voltage outputs in the 24-80 v range, is that correct?
It depends on the voltage of the drivers you're using. Most drivers that come in the eBay kits are up to 48V, drivers like Leadshine AM882 (now superseded buy AM806 drives I believe) will handle up to 80V but you have to take back EMF into account so dont run at more than 72V, mist on here will power these with a DIY PSU that gives out 72V....

Sent from my HUAWEI VNS-L31 using Tapatalk

Smokie555
06-10-2016, 12:10 AM
I've taken on board everything above and looked around for something more suitable than my Lagun. I've been offered a Bridgeport Interact Series1 Mk2 that in in good nick but has faulty electric's. I might be able to do a deal to trade my Lagun against it and wondered had anyone converted one of these to Mach 3 and modern electric's?

njhussey
06-10-2016, 10:40 AM
I've taken on board everything above and looked around for something more suitable than my Lagun. I've been offered a Bridgeport Interact Series1 Mk2 that in in good nick but has faulty electric's. I might be able to do a deal to trade my Lagun against it and wondered had anyone converted one of these to Mach 3 and modern electric's?

That's a perfect machine to drop modern electronics in.......

Smokie555
13-11-2016, 11:51 PM
Well guys the Lagun is away and the Interact is in the garage. It was confusing at the start because as soon as you powered up, the spindle ran? I couldn’t stop it or control its speed as it didn’t respond to the tool call/stop etc commands. Finally I changed 2 of the supply phases around as the spindle was always turning backwards on start up and that really helped as I could now control the spindle on and off and the speed, I even managed to do some milling manually which was great.
The problem now is she keeps tripping the RCB in the garage which I swopped from a 100mA to a 300mA job but it didn’t help. Unfortunately it's not 100% consistent, but the pattern seems most often when I move the X axis but sometimes it as soon as I press the orange power enable button.
I find it odd that there’s no neutral connection on this machine and I wonder if it’s using the earth as its neutral and is this triggering the RCB? I’m running off my 5.5Kw rotary convertor and never had tripping problems with the old mill which I think had a neutral. Any idea’s
1960819609

m_c
14-11-2016, 12:32 AM
No neutral on 3 phase machines is perfectly normal.
Tripping a 300mA breaker would suggest there is a fault somewhere. First thing to try would be to power it up, then move/shake any wiring you can get access to, to see if that causes it to trip.
Next thing would be to gradually isolate things in turn by pulling fuses, to see if you can narrow down the fault.

Smokie555
14-11-2016, 03:48 PM
Right I'll give that a try tonight, cheers

komatias
14-11-2016, 05:10 PM
No neutral on 3 phase machines is perfectly normal.
Tripping a 300mA breaker would suggest there is a fault somewhere. First thing to try would be to power it up, then move/shake any wiring you can get access to, to see if that causes it to trip.
Next thing would be to gradually isolate things in turn by pulling fuses, to see if you can narrow down the fault.

Tripping an RCD means you have leakage current to ground. This could potentially be fatal so disconnect the machine and test which of the power or signal wires are shorting to the chassis. On my KRV it turned out to be the motor. Took it to be repaired and all it needed was a wash.