Delrin or HDPE, which did you use?

[Glidergider]

I'm about to buy some plastic. My MDF adjustment blocks popped a thread yesterday so its time to rebuild in plastic. The plans call for delrin but I've seen several posts to buy HDPE.

On the McMasterCarr.com web page, I was able to determine that Delrin has a tensile strength of 10 ksi while the HDPE is rated at 4 ksi. I don't see any more distingishing atributes for these two product except price.

The Delrin cost $53 while the HDPE costs only $17. I wish I could make this thread into a poll. I'd really like to know what you guys are buying.
thanks,
Dave

[datacop]

HDPE:

Very easy to work with...

Sam's Club cutting board, 15" x 20" x 1/2" for $11.32 (I just bought some tonight)

more than enough to make all the adjuster blocks you'll need.

[Madclicker]

I think HDPE is better for mounting and structural because of price. Acetal (Delrin) and UHMWPE are better for wearing surfaces because they are self-lubricating. Just what I can gather.

[the__extreme]

I'd use the HDPE (or even UHWM http://www.paplastics.com/polyethylene.htm) instead of Derlin (http://www.paplastics.com/acetal.htm). Those are just the links from the local business I deal with. Derlin has slightly lower friction & thermal expansion, and the PE's are more resistant to wear. It goes along with the strength and elastic modulus, but I think Derlin is a little harder than HDPE also. I think you'd be fine with either material, so might as well save yourself some money and go with the cheaper of the two, as others also suggested.

If you're happy with the current MDF blocks, you could always bore out the thread holes a little and insert some T-nuts. They won't strip.

- Shawn

[SCHootie]

I want to make my own acme lead nuts, am I correct choosing delrin for these?

[Madclicker]

Originally Posted by SCHootie I want to make my own acme lead nuts, am I correct choosing delrin for these?

I think so. I used UHMW and am still using them, but I think acetal is the recommended material.

[SCHootie]

Maybe I'll try the UHMW to make sure I can produce a good lead nut, then do them in delrin if the UHMW wears out.

[pinemartin]

Hi All
Want to build a 3 axis milling machine for routering out letters and art work in wood. bewteen 5cm and 8cm deep. can anyone point me in the right direction. been told to check out forums but there are what seem like thousands, hard to know where to start. something rigid and of course user friendly. worked loads in autoCAD, but not with cnc, so easier the better.
Dave. Scotland

[tajord]

Hi All Want to build a 3 axis milling machine for routering out letters and art work in wood. bewteen 5cm and 8cm deep. can anyone point me in the right direction. been told to check out forums but there are what seem like thousands, hard to know where to start. something rigid and of course user friendly. worked loads in autoCAD, but not with cnc, so easier the better. Dave. Scotland

You probably can start with downloading the free jgro plans, a good "starter" cnc, you'll find them here, also you can view the threads of those who made this router and see what you think, here the link:
http://www.cnczone.com/forums/jgro_router_table_design/

Good luck.

Jordan.

[Glidergider]

The price for UHMW in the 12x12x3/4 size is $15.64. Its tensile strength is 3.2 ksi.

Delrin 10 ksi, $53
HDPE 4 ksi, $17
UHMW 3.2 ksi, $16

It seems the cost is proportional to tensile strength.

Originally Posted by SCHootie Maybe I'll try the UHMW to make sure I can produce a good lead nut, then do them in delrin if the UHMW wears out.

[Glidergider]

I'm curious, how do you know your cutting board is HDPE?
I used a cutting board for my 1/2 inch pipes. Actually mine was slightly less then 1/2 thick. I had to use some washers/spacers under the mounting screws.

I've looked everywhere for a thicker cutting block, but can't find one.

Originally Posted by datacop HDPE: Very easy to work with... Sam's Club cutting board, 15" x 20" x 1/2" for $11.32 (I just bought some tonight) more than enough to make all the adjuster blocks you'll need.

[datacop]

If you look at the image.. the first bullet point reads:

Durable: High Density Polyethylene

These aren't quite 1/2" either I measured them last night and they are more along the lines of 7/16".