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Messages - Davek0974

331
General Mach Discussion / Re: Bridgeport Knee Mill Conversion?
« on: April 01, 2018, 08:31:06 AM »
Thanks, I have made some progress now,

I had too much control of the wrench - removing the bottom bar has allowed it to move easily now.

The Torx has better torque rating than hex - I have modified the head a bit with the grinder and that has allowed it to mate easier now.

I am trying to find my PLC software disc so i can set up a simple control logic to get it cycling, its here somewhere.........

332
Yes, feed-rate override is dodgy as hell, I'm on v066 ;)

Its ok for a slight tweak while running but i always return it to 100% at shutdown.

Its not so bad <100% but not good >100%

333
General Mach Discussion / Re: Only X-axis motor is working
« on: April 01, 2018, 03:26:30 AM »
I would NOT go with Nema 34's - they are big, slow and need a serious setup of power supply and drives (high voltage/high power) to make them dance. If i were calculating I needed a Nema34 I would switch to AC servo's without further thought, a small AC servo can out perform a Nema34 easily.

IIRC the average "good" setting for micro steps is 1000 but it can be anywhere you want really, just remember that the higher you go, the faster Mach3 has to generate pulses - theres a limit (if you are using M3 to generate pulses that is)

Definitely belts as mentioned, another good profile is HTD5, very common and no backlash, its the shape of the teeth that matter, anti backlash belts generally have round profile teeth whereas the old ones had trapezoidal shapes.

Getting the balance between motor power and machine build is pretty much impossible first time - the calculations are horrendous so most builders think they need oodles of power and look to Nema34's etc - this then opens up a world of pain because you now have speed issues and your machine, although it can easily break a 25mm tool off, cannot move very fast when needed ;)

On most machine builds, It seems the most common solution now is for Nema23/4Nm on something like a 70v power supply with good anti-resonance digital drives. I have these on my plasma table, and even though I'm only running 48v it can certainly shift when needed, One on X and two on Y, Z has a smaller 3Nm motor. This is gear on rack drive so not good for milling etc but adequate for plasma which has zero axis load.

334
General Mach Discussion / Re: Only X-axis motor is working
« on: March 31, 2018, 04:46:52 PM »
The extra vibration at certain speeds sounds like resonance.

Mass i.e. a load should alter that but sometimes you have to work round it.

Steps per rev is usually fixed and written on the motor - generally 200 or 1.8deg per step, do you mean you set micro steps to 400??

335
General Mach Discussion / Re: Bridgeport Knee Mill Conversion?
« on: March 31, 2018, 10:38:50 AM »
Ok, so i finally got i all bolted up and the new drawbar made, mounted on the mill and, well clearly I still have work to do :(

The idea of allowing the wrench to fall will not work as the mechanism is not slack enough to let it - ok so we go to plan B and use air to push it - this works ok.

Next, the idea of not starting the impact until the Torx bits mate will not work - the Torx bits jam instead of mating about 75% of the time, might be able to improve this a bit by grinding the profiles a bit, will save that for later.

Next, with the wrench being held down, you cant easily insert a tool as it needs to push the drawbar upwards, but the cylinder is pressing it down so it risks cross-threading etc.

So I guess you MUST release the wrench after the tool is released? - I have no idea of the cycle here, all the videos just show it working, no real detail.

Does anyone know what i am missing here - anyone actually built a power drawbar for a threaded tool holding system like BT30??


336
General Mach Discussion / Probing - what would i need?
« on: March 31, 2018, 06:12:16 AM »
Hi all,

I'm currently using a Haimer 3d taster for setting my work coordinates, works well but its manual ;)

What would i be looking to get to setup auto edge detection routines and I guess I would also need to setup auto tool height setting as i currently use an off-machine tool height setter and the two are relative are they not?

I have watched some u-tube stuff but they all have multi-million £ Renishaw kit and thats just fantasy for me :)

Is there a workable budget setup?

337
General Mach Discussion / Re: Only X-axis motor is working
« on: March 30, 2018, 12:16:42 PM »
I think a lot of the problem might be that I hooked up my 8 wire steppers wrong.

I, mistakenly, thought I just needed 2 of the 4 coils wired and isolated the other 4 wires. It turns out I need to hook them all up either unipolar or bipolar connections.
The trick will be to find out which wires go to which coil.

These are 23LM-C304 motors. I still haven't found a color coded wiring diagram for them.

I'm not ignoring the advice of the PS issues. I just think I should have better results (even if not perfect) than I am.

Is that number correct?

Here is data for 23LM-C304 motors and it only shows 4 wire/2coil ???

http://web.archive.org/web/20050224182758/http://www.taxibooking.net/23LM-C304-51V.pdf

338
General Mach Discussion / Re: Scripter Compile Error bites again :(
« on: March 30, 2018, 12:09:20 PM »
Still working ok, I think I can safely recommend anyone that is suffering the random compile error to save all their macros as .mcc ones.

339
General Mach Discussion / Re: Bridgeport Knee Mill Conversion?
« on: March 30, 2018, 12:05:40 PM »
Still working on this :)

I have most of the parts for a power drawbar assembled now.

My idea is to let gravity do the down stroke - the theory is that it will make installing tools easier if the drawbar can lift a bit when the tool is loaded. If not then i can either use an air downstroke with air lift, or air downstroke with spring lift.

No ideas about control yet, I have various tiny PLC's on the shelf - would make it easy possibly to add the ATC later or i can add to my CSMIO setup. First off will just be a button or two and solenoid valves.

I'm using two valves - i want the wrench to drop first, then the power to be applied. The wrench can stay down until the next tool is fitted i think.

340
General Mach Discussion / Re: Only X-axis motor is working
« on: March 30, 2018, 03:13:16 AM »
I think a lot of the problem might be that I hooked up my 8 wire steppers wrong.

I, mistakenly, thought I just needed 2 of the 4 coils wired and isolated the other 4 wires. It turns out I need to hook them all up either unipolar or bipolar connections.
The trick will be to find out which wires go to which coil.

These are 23LM-C304 motors. I still haven't found a color coded wiring diagram for them.

I'm not ignoring the advice of the PS issues. I just think I should have better results (even if not perfect) than I am.

Hi, been following this thread from afar...

That is a major blooper right there - with only two coils running you will certainly get poor results at low speed due to the lower momentum of the rotor - once running at speed it will overcome the missing steps, of course you will only get half or less power from them ;)

I am unsure of the PSU options here - I have three machines all running on switch mode PSU's ranging from a plasma table to a large mill with servos, all run ok. One of the leading UK suppliers recommends SM PSU's for their drives/motors as well.

However, that being said, I do have the parts for a linear PSU on hand for my plasma table as they are pretty tough on electronics and also could do with a little more voltage that SM PSU's do not offer. When you have larger motors and high acceleration settings I do think a linear PSU is good as they can give much higher surge currents faster than SM ones but with small motors/machines then easy is the way forwards I think.

Wiring your motors correctly/fully will likely fix your issues ;)