[sd80mac]

I am currently building a Solsylva 10 X 9 machine, and while the build is going together okay, I already know that this machine isn't going to fit all off my needs. I will be building another (bigger) machine after this one with a cutting area in the neighborhood or 12-18 by 24-48". On to my question: For those that have built machines using MDF, had you ever considered using pre-primed dimensional MDF? Also, is there any difference between it and MDF in a large sheet format? I don't have a table saw, so the dimensional MDF would take care of ripping, which also equals less MDF dust!

Donnell

[harryn]

I have not built a cnc router from mdf, but I have built other items - in the past. I don't use mdf for anything anymore.

Yes, MDF does have some advantages, but IMHO, I would rather use hardwood faced plywood. It has nearly the same tolerances, a nicer face, equivalent edge quality, and much higher resistance to water. Yes, it is $ 50 / sheet vs $ 10 / sheet, but it seems like that is still a relatively small part of the overall build cost.

The difference in circular saw blade life and other factors make it well worth the difference.

[DonFrambach]

If I were to build a wooden router, I'd look into bamboo plywood which seems to have some nice characteristics. Here's a build log that used bamboo plywood with great success: http://www.cnczone.com/forums/cnc_wo...t_started.html

Yes a table saw is great but you can cut plywood and mdf very precisely with an inexpensive circular saw and an inexpensive shop built or commercial quide. I have a table saw but make my first cuts on large sheets with a guided circular saw so I don't have to wrestle bulky (and heavy) sheets. Here is a link to a commercial saw guide: http://www.rockler.com/product.cfm?p...4&site=ROCKLER but you can make one for a lot less.

[JerryBurks]

.........Here's a build log that used bamboo plywood with great success: http://www.cnczone.com/forums/cnc_wo...t_started.html........

That is my machine with the bamboo frame. I am very happy with it and can recommend it but would add some comments: The bamboo plywood is an excellent technical choice due to the rigidity/weight ratio, machinability and excellent fastener holding. But it is not cheap (about twice the price of good quality Baltic Birch) and if you don't live in an area with good specialty lumber supply the shipping will only add to this. The other extremely important thing is to use only the natural color bamboo plywood. There are grades available called "carbonized" or "caramel" that are heat treated. They may look prettier but the treatment degrades the stuff that binds the fibers together. It splinters badly and is overall much weaker than the natural bamboo.

[sd80mac]

Hello Jerry, Don and harryn,

I appreciate the advice on using bamboo ply, however, just hearing that the cost is twice that of standard Birch, Oak, or Maple ply is a huge deterrent! My goal was to try and make construction of my next machine a little easier based on the tools that I do have which include a drill press, circ saw, router, miter saw, cordless drill, and plenty of hand tools. MDF seemed a natural way to go because, for one, its inexpesive, and second, I've seen numerous succesful designs featuring MDF as the main structual building material/component which boosts my confidence in using it myself.

I just wanted to know if there was any major difference between MDF sheet and pre-primed MDF dimensionally cut boards other than the primer?

Thanks again,
Donnell

[jckstrthmghty]

I just wanted to know if there was any major difference between MDF sheet and pre-primed MDF dimensionally cut boards other than the primer?

There are different quality levels of MDF. Not sure about milled MDF like the type found in moldings. They seem lighter but I've never tested.

No worries about using MDF for your cnc router frame is used within it's structural limits. You can build a great machine with the stuff. Ensure you use proper ventilation when cutting. Atleast a dust mask. It's nasty stuff.

[louieatienza]

I had found, using pre-primed MDF on the field, that it's less dense than the sheet stuff. Then again, the Solsylva plans I believe call for some boards to be screwed on edge and MDF might not be the best choice for that. If you want pre-primed, you might want to look into pre-primed finger-jointed pine which is stronger, denser, and can hold screws better.

Most machines designed primarily out of MDF usually also use some form of reinforcement for edge or end joining, whether it be threaded inserts, barrel bolts, t-nuts.... Since there is very little material in the 10 x 9 anyway, I'd get dimensioned hardwoods (also availabe at the big box stores).

The glue in MDF contains formaldehyde, yet another reason to not use the stuff if possible.

[sd80mac]

Hi Louie,

I'm already in the middle of the Solsylva 10 x9 build. The Y-axis base and table are complete save for the leadscrew and drive nut. Most of the holes on the other components have been drilled, and are awaiting assembly. AB nuts and screws are waiting on additional funding!

The next machine will be similar to a Joe's 2006 or JRGO in scope and style, but more customized to suit my needs!

Thanks,
Donnell