(small)Pictures of my cnc(taken with a phone)
The third one shows the new gantry side cut using this machine. The forth was a test.
Table size at the moment is 500x240x75
Printable View
(small)Pictures of my cnc(taken with a phone)
The third one shows the new gantry side cut using this machine. The forth was a test.
Table size at the moment is 500x240x75
Looking good mate, whats the ganrty side for machine two or ?
Its to update this machine to make it neater, also have exact slots for the leadscrew bearings and bearing assemblies.Quote:
Originally Posted by Lee Roberts
Nice little machine there bro I like it, thats what its all about glad you have it working. What did you use for the leadscrew and nuts ?? nice job.
At the moment its using m8 threaded rod and delrin nuts. My upgrade to trapazoidal leadscrew and delrin anti backlash at some point to gain some speed. Running at 24ipm at the moment. Slow but accurate.Quote:
Originally Posted by Kammo1
Fine drive nuts they are to ;).
Actually quite a bargain given how much messing about was involved to make nuts before. The best thing about these is how easy they are to mount.Quote:
Originally Posted by Lee Roberts
Have you thought any more about making round ones with a flange(im sure thats what they call the surrounds) or even better antibacklash ones using a split end and a spring?
I dont have a lathe so i could't put a flange on them :(
Would a wood lathe cope cutting delrin ?
Yes i could, good old fashion hand tools.Quote:
Originally Posted by skittles
http://i16.ebayimg.com/07/i/000/8c/1f/8cf4_1_sbl.JPG
I will be making some ali round standoff's this weekend so this is how i will be doing it....using a Center Square.
this is quite interesting for a cheap way of making a lathe or even a 4th axis
http://www.axminster.co.uk/product-A...athe-21279.htm
I see, well ill give it ago and see what comes of it. I'v got my eye on a few lathes on ebay so hopfully i can win one of them. One of them is just down the road to me and looks quite nice.Quote:
Originally Posted by skittles
Yea that could be an option, ill would only really need a small one.Quote:
Originally Posted by progomez
The options are endless :), i dont really think there is a market for round drive nuts of this type anyway. I'v seen them listed befor and not do very well, in the ACME or the trapezoidal they may do "ok", i notice dice sells them like that not seen many sales on his feedback for them tho.
true as its easier to mount them in a circular hole.Quote:
Originally Posted by skittles
Slightly redesigned the gantry sides using the original. Will also be building a enclosure to keep the mdf dust in.
Problem is the noise that my cheap router was making was from the lower bearing. So will need to buy another router to continue the redesign.
Machine was cutting quite well except found out it was loosing acuracy due to the bearing making the router cut in an slightly oval shape.
Next on the list is a router. Still deciding on either a kress fme 800 or a trend t4. The trend is cheaper to service.
Also decided on upgrading all axis to trapezoidal although cant decide on 10x2 or 12x3.
Lee, can you make trapezoidal delrin nuts?
Aslo can my 1.85 motors run trapezoidal screws? Do they have enough torque?
Yes. I designed it that way.Quote:
Originally Posted by skittles
Cut it out of 18mm mdf with 4mm deep cuts. Took about 20mins a side. 600mm per min
havent been using this for a while and now have started purchasing parts for a "better" version.
I have decided to build another to try and rectify the main problem I found when using it which was :
1. Speed/ the m8 threaded rod was too slow (although not bad for the price. i have purchased 3 10x2 delrin nuts off ebay for £9.99. This should nearly double the speed.
Also Im thinking of buying this kit http://cgi.ebay.co.uk/linear-bearing...3286.m63.l1177
Any reason why not. it seems cheap and combined with some trapezoidal leadscrews from merchant dice it should only cost me around £120 for a 1000x700x300 linear bearing machine which should cut 3'x2' peices easily. Can anyone see a problem with the kit? seems cheap.
I also bought a new router a while ago kw800k b&d , off ebay, which will replace the cheap one which eventually burned out.
Im also thinking of what to do to minimise the noise.
Dont do it... the unsupported rail over a 1000mm length will flex badly. You need supported rail for the main 1000mm run and ideally for the 700mm one too.Quote:
Originally Posted by progomez
STOP DONT DO IT !
As Irving said, 16mm rail over those lengths will FLEX ! NO QUESTION !
You need to look at bigger rails or go with supported rail, sorry.
Thanks for the replies. What would be the maximum length for the 20mm and 16mm bearings as they seem quite cheap, at least for a small cnc.
No problem on the length of the rail for the bearings mate, irving will be the man when it comes to the maths on rail lenths as he has looked into rail flex before.
If it was me and i was looking to use 16mm rail, i would only use it on the Z axis with an overall length of 300mm MAX. For the 20mm rail i would goto say 6-700mm MAX.
Irving if you please :beer:
ive got a few lengths of more substantial rail and block with end caps for sale 25mm i dont think that would flex over 3ft! but i could be wrong:whistling:
How much would they be?Quote:
Originally Posted by AdCNC
Hi, been away for a few days...Quote:
Originally Posted by progomez
how long is a piece of string? It all depends on the rigidity of the mountings, what they are bolted to, the spacing of the trucks and the weight of what is running on the trucks.
As a guide, a pair of 800mm long, 20mm round rail on SK20 supports at each end deflects approx 0.5mm under a 10Kg load. If thats your X rails, your Y/Z gantry and router/spindle is likely to weigh 15 - 18Kg! If you are carving shapes out of MDF then don't expect better than 1mm accuracy vertically or 0.5mm horizontally. For most things you'll want better accuracy than that.
I use 16mm rail on my PCB mill but thats a moving table, fixed gantry design and the load on the table is tiny. On that I get 0.05mm deflection under 4Kg of load which is purely cutting forces as PCB's weigh nothing!
I have decided to make a smaller machine to test out the delrin nuts I bought off ebay. They are 10x2d and round. How do people mount round delrin so it doesnt spin? Should i flatten one end.
I have bought some trapezoidal rod from merchant dice size 400,400,200. Im thinking of encasing the machine in mdf and trying out a moving table design. The size should fit on my desk and the casing should stop some of the dust and noise(my main problem with my original router).
Ill only be able to make items less than 300x300 but will be good for testing. thanks for the advice.
Quote:
Originally Posted by progomez
I have the same nuts. I drilled out a chunk of mdf the diameter as the nut, slit it on one side, drilled through and used a couple of M5 bolts and M5 teenuts (captive recessed nut) to put the 'squeeze' on the delrin. 4 mounting holes in the corners allows ot to be bolted to the underside of the table/gantry/etc.
Thanks for the reply.Quote:
Originally Posted by irving2008
Would it be worth me shaving one side flat? Does the mdf hold it solid? have you got a picture of it?
Also is a moving table design better for accuracy?
No need to shave it, it holds it fine, just roughen the mating surfaces. Can use some loctite if need be. My cutting forces are low.Quote:
Originally Posted by progomez
Sorry no pics, I didnt take any but I might have the first trial one somewhere....
I dont think moving table v moving gantry is ab accuracy issue. Moving table (in X only on mine) is easier to implement in my view and with lightweight workpieces and low cutting forces (e.g. PCB milling) can get away with lower cost unsupported rails.
Ive picked up a cheap wood lathe with 4 jaw chuck off ebay so will try and make a ridge on the delrin nuts (once I figure out how to centre the nut)
I also decided to make a smaller 400/400/200 cnc and then in time buy one of the kits off ebay (from china) which has the supported rails and make a 4'by2' cnc.
Ive also joined a cnc course at my local college. Its shows how to manually program haas machines but also in time Im hoping to be able to use these machines to mill some parts out of alu.
To centre the nut you need a dial gauge and stand which can be got off ebay relatively cheaply. basically the trick is to adjust one pair of opposing jaws until rotating the chuck 180deg produces no offset, then repeat for the other pair.Quote:
Originally Posted by progomez
Be careful not to crush the nut tho...