Another BF30 CNC Conversion....

[photomankc]

Do you have a schematics on the reader box? I ask because I am thinking of doing a very similar homebrew remote display but using a Parallax Propeller chip to read the scales and do the display. My main question revolves around level conversion between the ~1.5v to 3.3V signals and the most effective way to do that. I really just need to pick up a scale a start experimenting.

Since the Propeller is an eight core processor I figure 4 can be devoted to collecting the data from the scales in assembly while the others drive the display, monitor buttons, and maybe do some calculations in the interpreted language.

[abfa9358]

I don't have schematics for my reader(I'm not that organised), I have the PCB layout and probably can find the component values used. I built my reader based on the information here http://www.compendiumarcana.com/caliper/ and here http://www.shumatech.com/support/chinese_scales.htm. It uses a PIC18F252 clocked at 20MHz which spends most of its time doing not much. My code occupies about 14% of the available code space.

Best way is definitely to buy a scale and start to investigate. I built everything up on a plug board to start with until I was sure the circuit was ok. A digital oscilloscope is really useful too. My reader does nothing clever in terms of DRO functionality. The scales operate in slow mode (~3Hz) and this has been fine for my use. I built a version which switched to fast mode (~50Hz) but found the jitter increased quite a bit. After that I think I got hooked converting my X2 mill to CNC so never progressed the reader as it work ok for me.

[abfa9358]

Well after some time there has been a bit more progress. I've pretty much finished the X axis motor mount(see pics). I'm quite pleased with it and its been good experience in terms of getting used to the new mill - which is turning out to be a very capable machine. I've also finished re-fitting my DRO system after a false start with one of the scale units.

I am now making the Y and Z motor spacer plates and two pairs of side plates to bolt directly to the mill. The Y and Z axes are less complicted than the X axis in terms of motor mounts.

I've also had to rebuild my control PC which runs EMC2 as the (almost new) hard disk failed. I put in a 30Gb solid state drive and in future I think I'll change over to an ITX motherboard if I can find one that runs EMC2 with a reasonably low jitter.

[LongRat]

Looks like your motor mounts are made of steel? Hardcore!

[abfa9358]

Hi Longrat,
Yes mounts are in steel, side plates and main plate are 1/2" and mount plate for the motor is 1/4". The mill chews through it no problem now that I've setup a flood (the workshop) coolant system. All big holes were bored out on the lathe.

[grf]

do you by any chance have any cad drawings for those plates? i have a bf-30 too and just received some servos and want to start conversion. thanks

[abfa9358]

grf
The whole motor mount assembly is modelled in 3D using Turbo CAD 17. I am quite happy to share this with you, need your email address and a file format you can handle. A few points to note:
Initially, I used my old X2 and my DRO system to measure the profile of the X axis plate on the mill. When I transposed this data in to TurboCAD I found that the errors in the measured data were unacceptable. To resolve this I made a number of suitably sized bushes, clamped the plate down on to the 1/2" steel plate blank and then spot drilled all the holes (3 x M8, 2 x Taper pin and one for the lead screw). I then used my centred the mill on the lead screw pilot hole and then pitched off for the 6 x M6 mount hole for the motor brackets.

The two 45mm deep side plates need reliefs adding to provide a bit of clearance for the two outer M8 fastener heads. This can be done with an end mill or a boring head but is not shown in the CAD. Without relief all fits together but there isn't much movement left for the bearing plate to float around.

Can I ask why servos on a machine this size?
Regards

[grf]

so if i got it right the drawings are not accurate enough

the servos i got are yaskawa 400w
i bought from fa-parts. i can tell you their service is second to none.
progress is very slow but at the moment i have all the electronic parts and going to start testing with mach3 (i would like to give the emc2 a try but scared i ll be lost). i am thinking of 3-1 reduction for x-y and 4-1 for z.
let me know if you need any more info

[abfa9358]

grf
3D model is close enough for a space plan and could probably be used to make the X plate but I felt it safer in the end to take the time to make some transfer jigs and use the existing plate as a template.

Photos of three motor moint plates attached

[abfa9358]

here...

[grf]

good stuff
keep them coming
cheers

[abfa9358]

A bit more progress... Y and Z mounts. Next a template to drill the Y and Z bearing plates on the machine followed by the ball nut mounts.

Oh, and the staircase is now undercoated and glossed!!