My flying gantry machine

[Lee Roberts]

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.

[progomez]

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?

[progomez]

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.

[irving2008]

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.

[Lee Roberts]

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.

[progomez]

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.

[irving2008]

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.

Hi, been away for a few days...

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!

[progomez]

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.

[irving2008]

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.

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.

[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.

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?