[CHB]

I will show here few ideas I did on my machine. Maybe, it is already somewhere - but maybe not yet.

first of all - Z axis
I used ballscrew 20 / 05

the body for the nut is from 2 parts - look at the one piece imbus M12 screw on the bottom. It is in hole -diameter 12mm, with plastic washer to hold it in place for assembly


imbus set screw ? (is that right ?)


the idea is to tighten this screw to M12 in centre through the M12 hole


by the way, if the three nuts are M12 - their head fits exactly to the round slot

[CHB]

BF20 uses MT2 for tool fixing (I do not plan toolchanger)
the tool is fixed in place by M10 x 1,5mm thread - part (114)
to release tool from MT2 - part (114) leans against part (112) - one turn moves about 1,5mm and it is sometimes difficult to release MT2 - often you must hit the screw on top.

Attachment 321900


I did replace part (114) and (112) as you can see in the picture (botom is the original (114))
When I tighten new part 114a by one turn, it pulls MT2 tool 1,5mm up and at the same time part 114a moves in nut M20x1,0mm - 1,0mm down. That is - I tighten MT2 tool by 0,5mm on one turn - now, just by hand I have enough power to tighten tool and mainly to release the tool - sometimes I use key to release - but never need to hit anything.
(M20 x 1,0 is the origin thread on part 112 - no need any other changes to machine)


Attachment 321902
Attachment 321904
Attachment 321906

[CHB]

My belt conversion

I decided to change to 3f motor + VFD -
get rid of noisy gear
get more reliable motor
get easier control by VFD

my choice was power motor (650W / 2,3Nm in size of 550W motor)

1. elektromotor 1LA9070-2LA12
SIMOTICS GP LOW-VOLTG. SQUIRREL-CAGE MOTOR IP55,
WITH INCREASED RATING 2-POLE,THERM.CL.155(F)*
SIZE 71M ALUMINUM ENCL.
3 AC 50HZ 230VD/400VY * 0,65 KW 2750 ot.
3 AC 60HZ 460VY * 0,75 KW
220-240/380-420 (50HZ)

belt - HTD5M x 15mm x 450 mm
pulley motor - 64 / spindle - 36 center distance - 97,5 mm max speed 9778 at 100Hz
pulley motor - 30 / spindle - 68 center distance - 97,9 mm max speed 2426 at 100Hz

in practice - over 6000 the big ball-bearing on top gets hot
and top speed is about 8000 - I have 750W VFD and it has no more power
sometimes I run motor around 15Hz (speed 350) and motor does not need external cooling

for me - I am satisfied with my belt conversion

chart - Nm / speed
Attachment 321908

Pulleys and shield are made by 3D print / ABS - it is in use for about 30 hours of work without any wear (it is hobby machine :-) )

Attachment 321910
Attachment 321912

[Chris600]

Nice beltconversion.

I am planning for something similar. How have you connected the pulleys to the spindle?

[CHB]

one part glued to spindle (take down the part with magnets)

Attachment 344796

on it there is collet with angle same as on sheave

Attachment 344798

and fixed with nut M40 x 1,5 (holes in it to tigten)

Attachment 344800

OK ?

[Chris600]

Thanks for the quick answer.

I have to take it a part som mayby I understand it better

[CHB]

on top of part "206" I had ring with 4 magnets for measuring spindle speed - I did remove it (maybe you have another detail for measuring spindle speed)
(I measure speed on top of the cover - little blue dot on picture not ideal, must redo it)

Attachment 344820


and the left side of this - I put inside part 206
(on the right side there is thread M40 x 1,5 for nut)
(the dimension 19,50 is for the collet


Attachment 344822


take it as princip - if you need details ask for them

[CHB]

my new probe - after problems with clasic probe, where using collet to hold the probe gave me error up to 0,05mm + error of the probe

I decided to make the probe fixed to the mill body. Now repeatable accuracy mesuring position is < 0,015 mm. Mach3 macro calculates the exact position of "zero" from measured position by probe. The probe can mesure only X - Y direction, not Z
Second picture is cover, when the probe is not used.

[CHB]

Probe works wery well, it is easy to use, sometimes I do not have to take out the tool and I can measure with the probe.
https://www.youtube.com/watch?v=QiMnQvBB9-E

Belt drive with spindle speed up to 10 000 is useful
https://www.youtube.com/watch?v=KFbd7AjqFZ4

same part, milling machine used as a CNC lathe.
https://www.youtube.com/watch?v=q-rqWbE5U8k

[CHB]

my new flycutter as flywheel