[krazatchu]

Just starting milling some MDF parts today for a Gantry Router.
We have most of the Z designed and have started testing MDF for milling, fit, rigidity and all that jazz...

The machine will be mostly 3/4 inch MDF with some steel channel for support where required.
I think this will give the best combination of strength and dampening.

I'm detailing the build log on my website, the first post being here:
http://n0m1.com/2012/02/22/side-proj...gantry-router/

The Y and X will be supported round rail, I have a couple of ideas for doing that on the cheap without sacrificing simplicity and alignment.
When that time comes, we'll build it up to study the practicality of the system.

I'm also concurrently working on an open source DC Servo Drive kit but that's another story entirely...

Michael
http://www.n0m1.com
Krazatchu Design Systems

[HorridHenry]

I know MDF is cheap(dear in the uk) but on a whole and more rigid Derlin/Actal is not far off the same price and I would have opted for this material,plus it won't warp/expand with the humid tempreture change.

[krazatchu]

@HorridHenry

The build will be around 4x6 feet so MDF is the real price winner here.
Expansion from humidity will be accounted for by a few coats of paint...

Michael
http://www.n0m1.com
Krazatchu Design Systems

[jckstrthmghty]

I know MDF is cheap(dear in the uk) but on a whole and more rigid Derlin/Actal is not far off the same price and I would have opted for this material,plus it won't warp/expand with the humid tempreture change.

MDF and delrin are close in price in the UK? You either have very low cost delrin of very high cost MDF. Most likely very expensive MDF.

[OCNC]

@HorridHenry

The build will be around 4x6 feet so MDF is the real price winner here.
Expansion from humidity will be accounted for by a few coats of paint...

Michael
http://www.n0m1.com
Krazatchu Design Systems

Use epoxy rather than paint. Paint is a poor sealer against moisture.

Chris

[OCNC]

MDF and delrin are close in price in the UK? You either have very low cost delrin of very high cost MDF. Most likely very expensive MDF.

MDF runs around $20-$25 per 4x8 sheet here in New England. What is it in the UK?

Chris

[HorridHenry]

I get it from a local timber stockist and the price is....

8x4x18mm at $27.44 or £17.52 sterling without the VAT of 17.5% which brings it to £20.58? $40 somethink?

[krazatchu]

So what's a good price on a 4x8 x3/4" (19mm) Delrin sheet?
I googled around locally but will have to call tomorrow during business hours..

Michael
http://www.n0m1.com
Krazatchu Design Systems

[HorridHenry]

Michael,I'm not suggesting using derlin all over,just small parts like the gantry and its components.

[krazatchu]

We have made some progress on the design as well as accumulating some parts.
The Z is entirely 3/4 inch aluminum and the rest of the gantry is square steel tube and 3/4 inch mdf. I've attached a pic.

There are more pics and a write up on the current state on my blog:
http://n0m1.com/2012/03/17/cnc-gantr...g-bits-pieces/

Michael

[krazatchu]

The next progress installment has been blogged, heat forming some threads into bits of UHMWPE for a Z-axis leadscrew nut...



There is video of the process as well as a some testing with the drill:
http://n0m1.com/2012/03/24/cnc-half-...lting-plastic/

Michael
http://n0m1.com/

[krazatchu]

Wow, the 25mm round rail supported with 3/8" thread rod works really well and is cheap too...



I used the Z carriage to align the second rail and it runs beautifully. I think this is an excellent alternative to more expensive supported rail.
There is more info, process details and a video on my blog: http://n0m1.com/2012/04/23/on-the-ch...d-linear-rail/

Michael

[krazatchu]

Nice, the rails made it to Hackaday: Cheap and easy linear supported rail - Hack a Day

Though the comments aren't very nice :<

Michael