Upgrading a MAKKO M850 cnc machine ?

[the great waldo]

Hello All
I've got a makko 850 cnc machine with acme thread screws and was wondering if upgrading/changing to ball screws would make a worthwhile improvement. The machine has currently 16x4mm acme screws. the x travel is 800 mm Y travel 540 mm Z travel 125 mm. The power supply will supply 4 amps per stepper phase on x and y and 2 amps per phase on the z axis. I`ve bought two Leadshine em705 drivers for the x and y motors not yet fitted (the ones supplied with the machine were leadshine m542 (7+ years old) the power supply is 40 volts (300va) I'm doing woodworking (guitar making ) with the machine, learning by doing!! Any tips on improving the machine would be eagerly accepted. I'm using uccnc uc100 which was a great investment as the machine was virtually unusable with the original software supplied French partially translated into other languages (if you get my drift) I think Alan Turing would have had trouble figuring out the software as it was. Looking forward to any advice on whether it's worth upgrading the screws or any other part. The machine has not had much use but i'm slowly getting used to to it and my fear factor has reduced a lot in the last months with all the information on this site.
Cheers

Andrew

[Chaz]

Whilst I cant prove it without delving into some specs of the screws however Acme is not exactly accurate. We used them for 3d printers, they are OK to move things from rotary to linear but its nowhere nearly as good as a proper ballscrew.

Sure, there are better nuts available (delrin etc) but it simply cant be as good, surely? I would have guessed (and its a guess) that the tolerance difference must be large between acme and ballscrew.

[Neale]

I did a quick Google search for this machine and it looks as if the current version uses ballscrews, according to a French web site. I'm sure that ballscrews will be better than trapezoidal/acme - could make the machine faster, less load on motors, more accurate (less backlash). However, this does depend on the structure of the machine being able to take the increased loads without bending or twisting.

It looks as if the machine normally comes with a Kress spindle which might also limit performance. Another forum member (Cropwell) has recently improved his machine by adding an extra spindle mounting block.

The Leadshine drivers should be good, and if you wanted, you could then go to a 50V or 55V power supply for a little bit of extra performance, although again that depends on whether the machine structure will take the load.

[the great waldo]

Whilst I cant prove it without delving into some specs of the screws however Acme is not exactly accurate. We used them for 3d printers, they are OK to move things from rotary to linear but its nowhere nearly as good as a proper ballscrew.

Sure, there are better nuts available (delrin etc) but it simply cant be as good, surely? I would have guessed (and its a guess) that the tolerance difference must be large between acme and ballscrew.

Hi Chaz and all

would it make any sense to use a 20 mm ball screw or would 16 mm be stable enough also what pitch on the thread would be the best for a woodworking machine. I won't be using this for a producton machine as such. I've got a 2.2kw air cooled chinese spindle and Hitachi inverter which I also need to mount sometime. The kress motor runs ok for small parts but only goes up to 8mm cutters , hence the 2.2kw spindle. The machine frame itself seems pretty rigid. I'm in Austria so if anyone has links to good ball screw suppliers in Europe please let me know. Any information gladly accepted.
Cheers

Andrew

[phill05]

Hi Chaz and all

The machine frame itself seems pretty rigid. I'm in Austria so if anyone has links to good ball screw suppliers in Europe please let me know. Any information gladly accepted.
Cheers

Andrew

Andrew,
Take a look https://www.damencnc.com I have used them, very helpful guys.

Phill

[Chaz]

Andrew,
Take a look https://www.damencnc.com I have used them, very helpful guys.

Phill

+1 from me too.

[the great waldo]

Hi Chaz.
A bit more speed would be nice and cnc is all about accuracy and repeatability I pressume? I will probably just change out the x y screws. The question is are 16mm screws rigid enough for this size machine and what would be a good thread? spacing. The acme screws I have are 16mmx4 what are the differences using a 16mm5 or 16mm 10? Would 20 mm rails be overkill. Also would it be possible to use the existing end bearings /supports and have the ends of the ballscrews machined to fit? Or go with new parts? Obviously the ballscrew bearing will have to be delivered with the screw. I won't be doing any production work but mainly wood cutting and some light work in ali and brass.
Cheers.
Andrew

[Chaz]

Hi Chaz.
A bit more speed would be nice and cnc is all about accuracy and repeatability I pressume? I will probably just change out the x y screws. The question is are 16mm screws rigid enough for this size machine and what would be a good thread? spacing. The acme screws I have are 16mmx4 what are the differences using a 16mm5 or 16mm 10? Would 20 mm rails be overkill. Also would it be possible to use the existing end bearings /supports and have the ends of the ballscrews machined to fit? Or go with new parts? Obviously the ballscrew bearing will have to be delivered with the screw. I won't be doing any production work but mainly wood cutting and some light work in ali and brass.
Cheers.
Andrew

I'm probably the wrong person to ask about 'overkill'. My own machine uses 40 size rails and 32mm ballscrews but its overkill.

I'd think for what you are doing 16mm are OK. Depending on the length, you might want to consider rotating ballnut designs (the screw doesnt spin, the nut does) which is ideal for longer lengths.

Any pics of this machine? Seeing it makes it easier to think about options.

[the great waldo]

Hi Chaz
I've tried to get some photos from the web on my phone (no luck I think i'm too old )but if you google makko m850 the new version with ball screws is on their web site with some options. My machine looks the same and they dont seem to have changed the design.
Cheers.
Andrew
I just found some photos on ebay[ATTACH=CONFIG]