David G

Well-known Member
I need to make some long plastic guides for a work project, what plastic will mill nice and allow the part to slide easily? The guide will be about a foot long, I am looking for 3" wide bar stock, so I can mill a 2" by 1/4" inch deep groove in it.
 
My thoughts exactly. You "should" be able to find 2" x 1/4" without much problem.

Here's some results from a quick search:
https://www.usplastic.com/catalog/item.aspx?itemid=30945&catid=868
This is for a piece 1/4" x 2" x 5', $2.49 per foot, $12.45 total as it comes in 5' lengths.

https://www.mscdirect.com/product/details/52433604
$19.38 for 5' section

Seems Grainger thinks their stock is sumpin' special!! 1' length sells for $39.40 and 3' length for $116.00!!
https://www.grainger.com/category/p.../raw-materials/ecatalog/N-nxaZ1z0o076Z1z0o0vs
 
Yes, UHMW Polyethylene is great for low-friction against metal or wood.

It is available from many types of sources. ....Woodworkers' supply houses, plastic suppliers, and metal supply houses often sell UHMW cheaper than industrial suppliers like MSC or Grainger.

You did not specify what thickness you desire. ...MSC shows 3" wide in 3/8", 1/2", 3/4" and 1" thicknesses.

Hit the link for 1/2" x 3" x 48" UHMW at a very good price, if it meets your needs.
1/2
 
Just a side note. On steam engines the guides are steel with brass blocks. Was at a tourist railroad shop and a friend was telling me they use a type of plastic now instead of the brass. He said it wears almost 4X better. Crazy hu?
 
For cutting UHMW you want to use a brand new cutter. High quality and super sharp. UHMW is soft and kind of "gummy" to mill and if your tooling is the least bit dull it will throw up huge burrs. Even with super sharp tools, be prepared to trim some. Xacto knife is your friend there.

The "slipperiness" makes it a bit tough to hold onto. Cutting forces can easily pull it out of a vise.
 
My mill goes to 2100 RPM, I can use a small cutter many passes or large 1" cutter 2 passes.
 
Might be cheaper to create the "trough" with bar stock and no milling.
3" wide with 1/2" wide bars on top.
Or 2" wide with thicker 1/2" wide bars up against sides.

Then if a part tears up any parts you only have to replace the damaged bar.

Look at McMaster-Carr also.
 
You are right about some of the UHMW does deteriorates quickly especially any of it that is white but the black UHMW holds up really well. We have piping made out of black UHMW at work that has been exposed to direct sunlight for years and has not failed with up to 150 PSI on it. It will deteriorate quickly at temperatures above 150 degrees.
 
Thanks for all the suggestions.

I think I will not mill the channel, but instead make it in 3 layers, as is it does not require milling.
 

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