Shall i build this router?

[tomfish]

First of all, first post, many thanks for all the interesting reading up to this point! I've spent hours and hours here so far!

I'm considering getting started with a router build. I've attached some screenshots and would be grateful of some constructive criticism.

I want the router to complement my other tools, and make creativity in the workshop simpler to achieve! I'd like to be able to machine basic alu plate parts (up to 10mm), and carve in mdf and oak timber.

While sketching the design I have tried to rely on as few tools as possible during the construction. The main tool will be a pillar drill.

Usable area is 1250mm x 450mm x 75mm. I'm planning a glued mdf and alu plate design, similar to the one below.
http://www.cnczone.com/forums/showth...t=40433&page=5
So far the mdf is 12mm thick, and the alu sheets are 2mm thick.

I'm going for low budget using skate bearings running on 6mm thick cold rolled steel. I've seen many designs using only 4 bearings per axis, and these are very neat, but I'm going to keep it simple with 6 bearings per axis, all pulling directly against each other. I am hoping that this will make marking out for holes, etc, more simple. Also I would like to make a nice rigid machine, and I think this will help.

So, I've not yet decided to go ahead (still saving, and justifying it to myself). I'm thinking out loud really.

The main bits I'm worried about are the weight of the Y and Z assembly (lots of steel in this design!), and the length of the X leadscrew (1600mm). Also I'm a bit worried I've over-built it (I want it to be stiff, not fall through the bench!).

Any comments you have might get me doing some more thinking.

[Kipper]

Looks kinda cute! The heavier the better for non-moving parts!

[tomfish]

Thanks for the encouragement kipper. The base is the only non-moving part, and it will probably be an mdf box with internal bracing.

I labelled some sections tonight. I'm still thinking...

Tom

[Kipper]

Thinking is good...When you stop thinking.....Start worrying

[analogman]

So why are you using aluminum skinned MDF?

[tomfish]

I'm thinking the alu skins will help with the rigidity of the machine, as well as stop the mdf from creeping. The mdf would function as a lightweight filler (like the eggbox cardboard in an interior door), while the alu skin would take most of the load. I've also got a crazy idea about assembling initially without the skins, then using the machine to cut them.

There's a video of the machine I linked to earlier running. The acceleration is impressive. I'll repost the link below:

YouTube - CNC-milling a wrench holder.

YouTube - CNC-milling a wrench holder.

Perhaps I'm wrongly linking this acceleration/rigidity to tahustvedt's use of alu skins. He also used ballscrews and commercial linear bearings (neither of which I can justify at the moment).

[Kipper]

It may act as sound deadening too! 9 2mm skins of Al is a solid upright...I wonder if anyone has made "Alaminatiominium" yet?

[BobF]

I work in aerospace.
We use a material that is an aluminum skin on each side and a honeycomb in the middle. It is extremely light and also rigid. Quite often it is used to build interior items with a wood veneer. Looks like solid wood, but the honeycomb material makes up a large part of the pieces and they are very lite.

[tomfish]

Well, it's been a year, I thought I'd post a little feedback/learning...
I did the main build log on mycncuk, a UK based site. http://www.mycncuk.com/forums/showth...andwich-router

Learning:
1) My router's not overbuilt. I've come to love the solid torsion beam base I made.

2) The skate bearing carriages I made are fiddly to adjust first-time, but very solid and rigid.

3) MDF is not very rigid. One of the first jobs I cut were replacements to the Y uprights out of 18mm MDF instead of 12mm. I also added "round the corner" reinforcements to stop the gantry wobbling during y axis accel/decel, and cutting. A big improvement. No alu skins yet - the machine is only JUST rigid enough for alu so far... Alu skins soon....

4) If you're going with a similar design, make the depth of the Y axis support beam bigger (this is the bit that's 100mm in the screenshot in post #3). I'd probably aim at 200mm. I've replaced this 12x100mm section, with an aluminium bar.

5) Routers are noisy - buy some earplugs!

6) You will need a dust collection system immediately if you're cutting wood. Seriously, budget for it, and build it at the same time as the router.

7) One of the key concepts in the design was hiding the X rails and screws out of the way of dust and debris. This has worked nicely.

I'll post more as I go along....