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Look at the bottom picture here. Kits & Plans
The majority is MDF.
I think the biggest problem with using all HDPE, is that you can't glue it together.
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Hi there,
I'm continuing to research more into the 2006 R2 CNC build, but have a question. Is it possible to make the CNC entirely out of HDPE? Rather, is it recommended? I thought I read somewhere that it could cause extra back lashing/binding if I made it entirely out of HDPE.
If I only make parts of it our of HDPE, which parts are MDF? I assume most of the torsion boxes, but the gantry's and carriage are entirely HDPE, correct?
Thanks for reading!
Anthony
Look at the bottom picture here. Kits & Plans
The majority is MDF.
I think the biggest problem with using all HDPE, is that you can't glue it together.
Gerry
Mach3 2010 Screenset
http://home.comcast.net/~cncwoodworker/2010.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Thanks for the quick reply!
Perhaps there is a solution for an all-HDPE Joes 2006.Originally Posted by ger21
Check out the TAP video on PolyWeld at YouTube
Hi all,
Is there a list of which parts are MDF and which are HDPE somewhere?
Thanks!
you could do it but wouldn't make any sense. MDF is used for it's economy factor. That much hdpe would not be cost effective considering the 80/20aluminum builds. Imagine how much that much plastic would weigh?
cpy911, motor mounts, z-axis, router mount, and gantry bearing adjustment block are hdpe. Joes site has the plans where you can examine all the parts.
My biggest concerns using MDF are:
1. It's very dense and needlessly heavy for such a poor structural material, compared to Baltic Birch plywood.
2. The effect of changes in geomery caused by variations in humidity. Sealing it to prevent warping and to get a good finish is difficult: it soaks up paint like a sponge!
Joe's web site is a bit contradictory and confuses matters. It shows several photos of 2006 machines made almost entirely of HDPE but the photo of the kit shows mostly MDF.
I would love to identify the faced plywood Norm Abrams uses for cabinates on "This Old House". It's covered with what appears to be a plastic laminate. Anyone know what it is called?
My shop is short on space. I like the footprint of the 2006 but prefer the mechanical structure of the 4 x 4 hybrid.
Not that it matters: I spent an hour trying to find the 2006 "Free plans" here at CNCZone and couldn't.
Thanks
L.J.
The pictures you see are the MDF painted white so it may look like HDPE at a first glance.
The Hybrid 5x5 machine is scalable. people have built it from a 2x4 up to a 5x10..
Thanks,
Joe
www.joescnc.com
joecnc2006 at yahoo
Joes CNC Model 2006 R-1 - CNCzone.com-The Largest Machinist Community on the net!
But you need to read down pretty far in the thread to find the R2 plans, versus the R1 plans. The R2 have the files in more formats, and are easier for some people to use.
more helpful info:
http://www.cnczone.com/forums/joes_c...s_2006_r1.html
http://www.cnczone.com/forums/joes_c...2006_mods.html
HDPE often contains stress, so finding some that is stress relieved is part of the challenge with that material. Sometimes you can find stress relieved pvc or poly "wet sinks" used in the semiconductor industry that have been scrapped out. Just make sure to test the material with pH paper to be sure any acids are completely neutralized.
MDF - while it is commonly used, I won't use the stuff for anything, not even to clean my shoes on. I think people either love it or hate it.
If it were me, I would build using some decent plywood, and then rebuild it with Al when / if you really think your machine meets your needs. Hardly anyone builds just one of these cnc routers without wanting to change something.
To all who responded to my request. . . . thanks!
MDF is, in my opinion, not really wood. It's used because it's cheap. Its density, compared to real wood, is heavy making things made from MDF needlessly heavy without imparting any structural benefit.
Working MDF without benefit of a mask is looking for trouble as it's formulation contains known carcinogens.
Painting any cut surfaces is difficult if not impossible without first applying several coats of sealant. It absorbs paint like a sponge thus making an already heavy material even more so.
I looked up specs on HDPE and shopped around. Average price for a .5" x 4 x 8 sheet is close to $200. I can get a 4 x 8 sheet of Apple plywood for about $130. Apple Plywood is the domestic 9 ply equivalent to Baltic Birch which I love. I can glue Apple with most any good glue, you can't do that with HDPE.
The only thing I can see that is needed is to adjust the widths of the half notches in the table ribs which are currently sized for the full half thickness of MDF. Apply plywood is 15/32nds.
One thing does puzzle me: does anyone know why Joe chose to make his longitudinal ribs two pieces instead of one?
I know I can create a table with a sealed inner chamber as I've done so in my shop when bagging composites. I'm toying with the idea of using pegboard for the top table skin and apply a vacuum as a method for holding material down.
Please note: the Mass Properties image reflects the estimated weight of the table when made with MDF and with top and bottom skins of quarter inch tempered Masonite.
Thanks to all who answered my questions.
L.J.
You should be able to get appleply in 3/4" nominal thickness (13 ply).
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