Re: marker pen driven over an 8x4 sheet help.
Quote:
Originally Posted by
Jonathan
I meant not a problem with belts for a plotter, but if you've done a plotter and it's wasn't then fair enough. There was a plotter at school we dismantled that was belt driven without further reduction...and the rapid prototyper, laser cutter.
Yes on small printer type plotter this would probably be fine because of the small Diameter pulleys but on a machine this size the diameters get large so obviously the circumference does giving a very large pitch.!
Take for instance a 20T pulley which really for 8ft machine is about as small has you'd want to go then direct drive pitch is 97mm.:eek: . . . . It's bit like putting F1 engine in a dumper truck, it will carry what ever you want and go like fuck but the bastard won't stop or go round corners. :dance:
Re: marker pen driven over an 8x4 sheet help.
So just to recap
Im building a wooden constructed belt driven plotter using these parts from:
http://www.ebay.co.uk/itm/CNC-Kit-3-...item2a14d75139
ive read some of the other posts and the talk is very technical is this kit above simple enough for a novice like myself, i have rebuilt engines but electrical jargon is scary to me ,but i can follow instructions well, should i bow out gracefully i wonder.
belts and pulleys what sizes would you recommend and were from.
free software from cambam ( can i just import dxfs and this software will control the pen as well as work out the tool paths?) obviously the pen will need to move in and out somehow Via the z control i presume.
do i need any other parts ? timber is not a problem the rest is.. has anyone got pictures i can take inspiration from i have some ideas but sure they will be way off what's really needed , if i new what to import from 3d content central into solidworks
i could assemble a plotter for you guys to giggle at !
Re: marker pen driven over an 8x4 sheet help.
Totally agree with JAZZ .
If that's going to be pen only there is no point to mess with ballnuts and screws. Belt is defenetly a way to go. I wouldn't drive it directly but made some reduction, but of course direct drive will work as well.
eg belt 3M pitch belt driven with 15 tooth pulley gives you 45 mm of axis movement per revolution of driving pulley. Reducing it further 5x gives you 9mm/rev. Driving it with stepper (after reduction) @1/2 step (400 steps/rev) gives you 0.0225mm resolution. I think its enough for your boat drawing or even for cutting
Driving it directly with 15 tooth pulley @1/2 step will give you 0.1125mm resolution
Just some example calculation -hope it helps
Re: marker pen driven over an 8x4 sheet help.
Re: marker pen driven over an 8x4 sheet help.
Quote:
ive read some of the other posts and the talk is very technical is this kit above simple enough for a novice like myself, i have rebuilt engines but electrical jargon is scary to me ,but i can follow instructions well, should i bow out gracefully i wonder.
hi Danny, the reason i bought this kit was because its cheap and like you im not to handy with the electrickery
i just followed the instuctions thay came with it and i was up and running, im not saying its simple but with those instructions and this forum you will get through it if your willing to stick at it and push on to the end :smile:
using timing belts is a winner of an idea to keep the price down
i get mine from here
http://www.beltingonline.com/polyure...5toch08jpn8j62
Quote:
( can i just import dxfs and this software will control the pen as well as work out the tool paths?)
not quite... you will import your dxf and use this sofware to create a file (g-code) that will have your tool paths feed rates etc and insruct your machine via mach3 sofware
im gessing you will be able to twist somones arm where you work and get them to help you with g-code ????
if your willing to use AutoCad to do your drawings it may be worth reading robins thread and trying his RCAD
http://www.mycncuk.com/forums/showth...5432#post25432
it may offer a simple alternative to G-code and is driven through a usb and might just be an absolute winner for avoiding the complexaties of CAD to CAM to Mach3
Re: marker pen driven over an 8x4 sheet help.
You could try the method where the board is supported with it's longest edge on the floor and a cable, up to 8+4=12' long supported at the top corners with a motor and pulley. The pen is suspended in between, so the cable makes a V-shape. By adjusting the length of the cable by spinning each of the motors you can get the pen to move to any position within the board. It's simple trigonometry to work out the relationship between pen position and motors. Then you enter those formula's into mach3 and it will run it as normal...
A standard belt driver plotter will probably be better, but since you're going to have to buy steppers and drivers for either you could try this initially as you only need a piece of string and a pen...
Edit: Wrote this post 2 days ago but forgot to press send!
Re: marker pen driven over an 8x4 sheet help.
Interesting link on the belting Mark.
Pulley pricing between T5 and HTD5 is pretty even but 6 metres of HTD belting is £94 against £45 for the T5
Something to bear in mind when pricing a job up
[edit] but HTD is cheaper all round when using stock belts, it's just the open length thats cheaper in T5
Re: marker pen driven over an 8x4 sheet help.
Quote:
Originally Posted by
John S
Pulley pricing between T5 and HTD5 is pretty even
I guess that's because there's a similar amount of material and machining time involved in each. It's the same process just a different cutter? Edit: I suppose the same could be said for the belts!
Quote:
Originally Posted by
John S
but 6 metres of HTD belting is £94 against £45 for the T5
Shame we can't also make the belts.
Good link anyway ... still want to find somewhere which sells HTD belts with steel tension members.
http://www.bearingstation.co.uk/
Something to bear in mind when pricing a job up[/QUOTE]
Re: marker pen driven over an 8x4 sheet help.
I have some surplus belt leftover from my belt driven CNC I made some time ago. Don't have too much pictures, in fact non, I think - they disappear in stomach of our samoyed puppy together with 2GB memory card.
3M 15mm wide and 5M 25mm wide-
ebay auction no 300608706166 and 300615411815
Pulleys and belts I buy from bearing boys good price, selection and fast delivery
Re: marker pen driven over an 8x4 sheet help.
Quote:
Originally Posted by
Jonathan
Good link anyway ... still want to find somewhere which sells HTD belts with steel tension members.
[/QUOTE]
The link posted by Wiatroda,
http://www.ebay.co.uk/itm/open-end-H...-/300615411815
Is for steel reinforced.
