Durable parts for machines

laserallthethings
sourcematerials
parts

#1

What would be the best material to use for a durable part in some type of CNC machine or other object requiring precision machining but high strength that can be cut with a Glowforge?

For example, making the plates and various mounts for a home made CNC. In this example build, the maker uses Garolite for the plates. He machined them with a router on the first version of his CNC made with MDF and aluminum brackets… Garolite is strong but has some problems as to suitability for lasers.

http://www.fortcollinscreatorhub.org/?p=554

Corian is pretty durable, but might not have the shear strength to withstand stresses. It is rather expensive and from what I have read, is not the most pleasant material to cut and engrave. I know plywood is used in many smaller CNC machines.

It seems aluminum plates are most often used in CNCs and they can be bought fairly reasonable with OpenBuilds, but of course they can’t be cut with a Glowforge,

I can see the Glowforge doing a first iteration to get a spindle CNC going and then switch to machined aluminum for durability like @karaelena has demonstrated. Part of it is that aluminum can be drilled and tapped as needed.

Any experience out there?

[By the way: I couldn’t to find the “carry this discussion over to a new topic” link. I’d have cross linked in the parts maker topic, but didn’t find it until after I created this. It’s under the Share button.]


How many "parts" makers among us?
#2

It really depends on how much durability you need. If you just need something to last long enough to bootstrap, high-quality ply (especially faced with something hard) or mdf could do it. Or non-acrylic plastic. You might have to cut/drill your aluminum gingerly.


#3

When I played a lot of paintball a ton of custom stuff was milled out of delrin. I’d say that is a pretty good start for durable material and I think would be my go to material for anything I want to be durable and sturdy


#4

I like Delrin as well for use on my Shapeoko 3. Machines very nicely with an extremely high quality finish (if you use quality end mills like the Amana “0” Flute type). Delrin’s not cheap stuff though.


#5

Delrin (generic name: “acetal”) is probably one of the better choices. It’s apparently laserable ( https://www.google.com/search?q=laser+cut+delrin&tbm=isch ) and it’s definitely a favored plastic for machining. People say it has low (or maybe no) internal stress which is something that causes other plastics (and other materials) to deform after being machined. My understanding is that it can also be injection molded.


#6

Yep, Delrin seems to fit the bill. You may be able to get some “second quality”, small air bubbles, Delrin to practice with before committing to expensive slabs.


#7

I hate to say it, but given the cost of acetal in thick sheets, you would be much better off with plywood, even if you have to remake parts as they wear out.

Or you could measure very carefully and make the most heavily stressed pieces out of Aluminum with hand tools. It is pretty amazing what you can do with a set of calipers, a band saw or jig saw, drill press, hand drill and a few files. In fact, once you have the laser you can cut very accurate templates out of paper and glue them directly to the aluminum.


#8

These may be interesting links for selection of wood when building wooden components:

https://www.woodgears.ca/hardness_test/index.html

http://tinytimbers.com/janka.htm


#9

I finally looked up acetal Yikes! MSCDirect has one square foot sheet of 1/4" at $25.00. Definitely understand why CNC first iterations are so often MDF.

That’s a good point about the hand work for the aluminum. Somewhere along the tool production line, there is a hand-made part buried in long-ago history.


#10

Agreed. Cut a template out of cheap thin mdf boards and then use a router with a flush trim bit / template bit to create parts in thick mdf boards, plywood or even aluminium. A jigsaw or bandsaw for an initial rough cut will decrease time spend routing.


#11

Are you looking for the “best” material to use to make a DIY CNC router? Or are you asking for the “best” material that the Glowforge can cut to use to make a DIY CNC router?

I was assuming an underlying part of your question was “imagine someone who owns few tools other than a Glowforge”.


#12

Perhaps best material is less helpful than what materials can be suitably printed with the Glowforge in making the plates and brackets that are essential parts of CNC machines. There seems to be a trade off with costly and durable, cuts great (delrin) and cheap and a possible temporary solution (MDF). It would have to be able to compete with ordering waterjet and milled parts from JoesCNC or another supply and design provider.

I like @brianfroelund’s idea of making mdf templates and then milling around them.


#13

One thing to remember about such temp parts is that they don’t necessarily have that many critical dimensions. Certain holes need to be of particular sizes and in particular relationships to one another (this is where you need to be really good, because even templated bits can wander). And certain flat surfaces need to be in know relationships to the holes (and the same across multiple pieces). The rest of the cuts can fall where they may, as long as they don’t interfere.


#14

Sticking this video here as follow up. Uses laser cut parts to make a shaft coupler for motor to lead screw.


#15

Delrin is an example of a POM homopolymer, whereas you’ll usually end up with a POM copolymer if you buy generic acetal. The characteristics of each are a little different, melting point being one of them. Overall, though, POM is an amazing material that I’ve designed quite a few machined parts from and I look forward to experimenting with laser cutting. Also, yes, injection molding and hot extruding are two of the most common methods for working with POM, but it’s also wonderful to machine on a mill or lathe. I don’t know a ton about laser cutting POM other than your best bet is probably going to be with natural white homopolymer–black sheets contain carbon black (probably don’t want to burn that) and I know some folks who have run into some really foul smelling copolymers when laser cut.


#16

Thanks for the info! I was under the impression that Delrin was simply a brand name for acetal. I thought it was roughly equivalent to Evian just being a brand name for water. How naive. :wink:


#17

You have considerable distance to cover before you approach my level of naivety :hushed:


#18

Evian is a generic name to you? interesting. Kleenex and google are my go-to examples.

Evian water is all bottled in the area around Évian-Les-Bains, France, on the southern shore of Lake Geneva. I spent a summer there as a kid, one town over, in Thonen-Les-Bains. There was a french-fry stand on the beach. It had the best fries I have ever tasted.


#19

“Water” is the generic.

Evian:water as Delrin:acetal


#20

Somehow missed this blog before. It’s not completely acrylic, but he uses laser-cut acrylic for the plates and and connectors and extruded aluminum for the rails. Utlimate end of the build is to make it strong enough to mill aluminum to replace the acrylic plates. This is path I wish to take. I’ve been slowly gathering the bits and pieces. Will probably use the bandsaw and MDF for the first iteration, but when the Glowforge comes, will see how that will improve things.

Transmogification in process.