Alternatives to MDF Please.

[Oldmanandhistoy]

Hi all
Thanks to this site I’ve completed my first cnc router. Would like to say to anyone starting out, it’s a steep learning curve but don’t give up. The end result is well worth the hours.
Well now I have the bug big time and am well into design improvements for MK II. I used MDF for the main structure of my cnc router which was built as a learning tool for MK II.
Anyway to the point of this post I’m hoping to find a better alternative to MDF. I could spend many hours searching the net for information on other possible materials but am hoping to tap into the many very knowledgeable people using this site and hopefully save my self and others a lot of time.
The most obvious answer I guess would be Aluminium but the most obvious isn’t always the best or the most practical for the amateur builder. So what I’m hoping for here is input from some experts or knowledgeable amateurs to make up a list of usable materials with some general information for machining said material, advantages and disadvantages to using them.
What I am hoping is at the end of this post I will be able to make some sort of table for the use of others giving alternative materials, pros and cons, tips and safety issues.
Please feel free to suggest any possible materials and/or give advice on using a suggestion.
I would like to say thank you in advance to anyone who makes a contribution to this post.

John.

[Supertigre]

John;

You got it in one. Aluminium is a great choice for the next step. It can be worked with the same tools you used to build the MDF machine, you may even be able to machine it with the machine you have with the proper feeds and speeds! It is much more durable, water proof (except for the electronics), and recycleable.

Guy
Sawdust-and-Noise.tripod.com

[InspirationTool]

Disclaimer: I haven't built a CNC machine.

If you don't like the aluminum option for reasons of cost or difficulty, give some thought to Applyply plywood. It is true dimension (.500, .750 etc) has maple faces and alder core plys and has a very good strength to weight ratio.

-Jeff

[Oldmanandhistoy]

Thanks Supertiger for your input.

Aluminium is probably the idea choice and you say I could use the same tools to machine it as I did the MDF. Could you or some one else reading this post elaborate on types of Aluminium suitable those not suitable. If I were to machine it on my cnc router would I need to use a coolant (would be a problem for my MDF router)? Any other considerations?

John

[Oldmanandhistoy]

InspirationTool

I have considered ply woods namely birch ply. Would you think there may be issues with movement due to atmospheric condition that a cnc router could not tolerate?

Thanks for your time

[InspirationTool]

I think you would have less problems than with MDF. You would still need to seal it though. Appleply is stonger and more stable than birch. And it is true inch measurement, which makes it *much* easier to lay out in autocad.

You can see the telescope I built with it here:

http://www.jeffalbro.net/astronomy/one-trip-dobsonian/

-Jeff

[Supertigre]

High quality plywoods (Birch and "Apple ply") are suitable for building small CNC routers but! they will not build a signifigantly stiffer / stronger machine than MDF and may have a small issue with changing humidity. To build a machine (MK II) to improve accuracy and solidity will require the move to metal construction. As John has already built a machine in MDF he already has the tools required to work in aluminium. Steel construction while arguably better then aluminium would also require a new shop full of tools.

Guy

PS I believe that for the most part "Apple Ply" is only available in North America.

[Oldmanandhistoy]

What I’m trying to do here is to build up a list of possible materials, their properties, suitability and characteristics for use in cnc construction.
While this will benefit me I am hoping others may use this to help them make a choice based on their availability to materials, machining capabilities and also budget.
I have read in a post somewhere some one suggesting possible plastics can anyone suggest anything along these lines.
Would tufnol be a possibility? Availability, suitability, cost and machinability?

While browsing this site I find Information in fragments and wide spread .I would like anyone considering possible materials to find lots of information in this thread.
I have benefited greatly from this site and would like to not only help myself but try to help others.
John

[2muchstuff]

If I was going to build one out of wood, I would use a Baltic Birch veneer plywood. I have seen 3/4" plywood with up to 15 plys. Great stuff to use, very stable but can be hard to find though. I get most of mine from shipping crates coming in from Denmark and Germany. Sometimes you can find it in specialty hardwood lumber stores. As for sealing it up I use a 2 part epoxy thinned with acetone (1:1) for the first coat and not thinned for the second and succesive coats.

I have seen somewhere in the gallery that there is a router made out of a phenolic resin. The gantry uprights were out of 3/4" sheet, red or pink in color.

The router that I'm building now it too big for the use of wood, I'm using aluminum and steel.

[joecnc2006]

HDPE (High Density Polyetheline)

Joe

[wizard]

Hi John;

I'm relatively new to the board and recently registered. Can't say that i've completed a CNC router table yet but do have experience in th eoptics industry.

One thing to consider is sheet PVC. This would be usefull in a machine that expects exposure to rusting fluids. On the other hand it is not particularlly practical cost wise and getting a sound stucture would be a challange.

Others have mentioned the various better grades of hardwood plywood. This would be fine for the first revision but you are past that now. However don't count this material out by any means, even if not used on MK2, it is an addictive material once you have worked with it.

One idea I've been flirting with is cast resin. I've seen a lot of machinery and metrology hardware made out of this stuff, that in its finished state looks like granite. Of course a big slab of granite is also a possibility In any event the idea is to literally cast you machine in an epoxy or similar resin. Sounds simple but I've not come across much in the way of howto material.

Another answer is to go with Metal construction. It is however much more invovled if you want to realize the full benefits. Some parts of the machine would benefit from weldments or castings though you could probably attack the whole thing with sheet goods. You do have to be thought ful though as a metal frame has to be stiff and requires a bit of though in design. Allied with a built up structure is the thought of using Aluminum extrusions, very $$$$$$$$$! While some would argue I don't have anywhere near the confidence in Aluminum extrusions as I do weldments.

Somewhere beyond the above would be a cast iron structure. But if you can cast an Iron project that big you wouldn't be here.

You should consider the possibility of casting some of your parts in metal (probably aluminum) to gain unitized parts. There is coverage on the net related to doing so. This might be something to reserve for MK2.5 though.

Then there is concrete!


the big reality is that your course of action may very well be dictated by your personnal tool collection. Or that of buddies and nieghbors. It makes little sense to plane around a weldment for example if your don't hat the tools to execute. I've focused a bit on weldments as that can allow you to build a really nice machine, but there are a whole host of other issues to contend with weldments. Bolted together assemblies can be really nice but to be done right are time consuming.

Dave



Dave.

Originally Posted by Oldmanandhistoy Hi all Thanks to this site I’ve completed my first cnc router. Would like to say to anyone starting out, it’s a steep learning curve but don’t give up. The end result is well worth the hours. Well now I have the bug big time and am well into design improvements for MK II. I used MDF for the main structure of my cnc router which was built as a learning tool for MK II. Anyway to the point of this post I’m hoping to find a better alternative to MDF. I could spend many hours searching the net for information on other possible materials but am hoping to tap into the many very knowledgeable people using this site and hopefully save my self and others a lot of time. The most obvious answer I guess would be Aluminium but the most obvious isn’t always the best or the most practical for the amateur builder. So what I’m hoping for here is input from some experts or knowledgeable amateurs to make up a list of usable materials with some general information for machining said material, advantages and disadvantages to using them. What I am hoping is at the end of this post I will be able to make some sort of table for the use of others giving alternative materials, pros and cons, tips and safety issues. Please feel free to suggest any possible materials and/or give advice on using a suggestion. I would like to say thank you in advance to anyone who makes a contribution to this post. John.

[ynneb]

HDPE (High Density Polyetheline)

Yep I must agree, I have recently been using a lot of plastics. Mostly recycled reconstituted polyprop sheets and I love the stuff. It routes smoothly. Is reasonably ridget, is cheap, has extreme chemical and moisture resistance and not subject to rust or corsion. Much cheaper than Alum, but less ridget than alum, however you just make the design thicker.