1.7*0.74*0.4m Mill / Router building...

[M250cnc]

Double Post

[blackburn mark]

Surely a timing belt for the outer gear would have the wrong profile.

i compleatly missed that,,, i think your right

iv got another one for you to ponder... there is probably somthing obvious iv missed but if you use a double sided timing belt you might be able to exit the belt through the outer gear wall (using small rollers maybe) to drive an output pulley, that
might solve the main stumbling block to the idea and give you a sturdy output (if it could be made to work)



it would make an interesting project but i think im going to admit defeat and try to get a second hand hi-tec drive :)

[blackburn mark]

ill do a sketch if i find time.

Why do you want such a high ratio anyway?

i want to cut holes and bearing recesses in a 50mm acetal cylinder and also engrave fine markings and im trying to avoid the complications of adding a disk brake... it feels like i might get the holding torqe i need at 50:1 (i should really do the maths)
i may well use timing belts and pullies, im not fully commited to one thing or another at the moment

with all the ice i managed to burn out my windscreen wiper motor so iv even pulled the old one apart to look at the worm gear as a possibility... thats 55:1 ratio, i think id struggle tameing the backlash on that though

[Jonathan]

avoid the complications of adding a disk brake... it feels like i might get the holding torqe i need at 50:1 (i should really do the maths)

Could stick with a worm drive and compensate for the backlash on that, either in software or use a split wormwheel sprung to eliminate backlash. If you've got 3nm holding torque then clearly that gets 150Nm at that ratio. So say maximum radius of 75mm, that gets you up to 2kN cutting force ... plenty.

iv heard this said a few times... im not sure i agree with that phil, surley the table only has to "equal and opposit" the cutting force and carry the weight of the job.... you could use blu-tac as long as it did just this :)

Yes, double sided tape is great for holding some things, especially PCBs. Effectively I would have 54mm of MDF, with some slots in it...plenty to carry the weight of the job I should think. Could try and calculate the deflection. I'm worried more about if I could do the bolts up tight enough without crushing the MDF. If I put a thin sheet of steel under the top MDF layer that should solve that.

Dad's still making legs for router - wooden frames are always his department. Going to go and help now...

[blackburn mark]

Jonathan, you have a lot to learn.:whistling:

ha!! i guess that means your just about done with learning phil :clap:

right!!! im off to stick my hand int fire :heehee:

[M250cnc]

ha!! i guess that means your just about done with learning phil :clap:

:confused: :confused: :confused: :confused:

Phil

[Jonathan]

:confused: :confused: :confused: :confused:

Just what I was thinking.

Jonathan, you have a lot to learn.:whistling:

I've got plenty of years to learn it Hmm, just worked out it's 7 years since I first used a milling machine - yikes I must be getting old.

Anyway, thanks for the advice so far. I'll leave the bed for a little while and have a think.

The legs will hopefully be done tomorrow, so all being well I'll have it running tomorrow night. Got to think of something to make with it now!

[blackburn mark]

Just what I was thinking.

ok ok,,, it must be a northern thing
i was feeling you were coming across a bit patronising phil
im sure youd get mdf to work if money left you with no option jonathan, maybe phil has arms like legs and would keep tightening those clamps till something broke

maybe you could make phil a touque wrench on it when your done

sorry phil :whistling:

[Jonathan]

Some pictures...

Legs:

Gantry side:

One X motor, need to tighten that belt:

Gantry side again:

Yeah my workshop is in disarray now:

[blackburn mark]

my workshop is in disarray now

looks well tidy to me:) i could live in that workshop