I’m looking to print some delrin-like material that can slide easily on 80/20.
Any thoughts on best material?
Delrin is plastic with both rigidity and tolerance for stress.
Abrasion resistant, too.
Sadly- no printable resin I know of can hit all three targets equally well.
Rigid has the closest properties to delrin… but both Tough and Durable out perform it in other aspects.
Here’s what I suggest- you can print with high precision… create a model that is multipart so that different parts capture different qualities and print each part in the resin best suited to that function… then assemble the result into a part with laminated construction to see if you can get better overall performance than any single resin offers.
I am planning on trying this with our Form2 to see how hard it is to make mixed media parts.
eg- rigid has a glass fill that makes it very hard- resistant to abrasion, itself, but also potentially abrasive to other components of an assembly. But what if you fitted Tough resin bushings inside the Rigid part to act as a smoother surface?
Or had a portion of the model that required more flexibility printed out of Durable.
or even imagine a laminar assembly of alternating plates of durable and tough? controlling the varied thickness of each lamination would offer a different result in terms of flexural strength,
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I’m thinking I might print a part in tough and use thin strips of Delrin to coat the inside that piece that slides
Let me know how that works- i want to do similar experiments when the need arises.
However, if its Strictly a sliding motion, then the tough might do alone.
We have to drill some 1" diameter 4 foot long holes- into large pieces of milled foam using a jury rigged long throw horizontal boring machine. We couldn’t find an auger long enough, so we fabricated a coring drill shaft out of copper pipe… the pipe was slightly smaller in diameter than the holes in the wood framing thru which we had to drill to insert the wood dowels that go in the holes… and I was worried about shudder or play allowing the shaft to wobble.
So I designed and printed a two piece bushing that fit perfectly in the gap between the hole in the wood framing, and the shaft of the copper drill… with about a 1.5 inch width to help stabilize the axis of the copper tube.
Printed in tough, we simply lubed the copper tube with a little spray silicone lubricant, and have been both spinning the copper shaft at 480 rpm AND sliding 4 feet of the spinning shaft axially thru the printed bushing, and the Tough resin is holding up remarkably well.
Our only concern is that we not HEAT the resin to the point of it breaking down… which is what the lube is for and why the relatively low rpm.
We drilled 15 holes so far and the resin seems to be fine. Each hole only takes about a minute to drill…
So you might try tough alone as well- just to see if it can handle it.
oh- and how did we fix the copper tube to the drill chuck dead center?
I modeled and printed in Tough a two part sleeve that fits the fluting on an old 1/2" drill bit…and features radial fins axially aligned with a slight taper near the tip… so you put the two sides on the bit, fitted to the flutes, and then forced it into the copper tube, which shaved a tiny bit off the axial fins for a perfect tight fit.
So the Tough not only served as the aligning bushing- it was the interface between a drill bit and the copper tube shaft that had to both spin the copper shaft and take the thrust of the 4 foot bore.
both parts did rather well
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@Sculptingman - I would be interested in seeing some pics if you can share them. Sounds like a fun little project.
Chris
These are the 4 parts modeled to make a driver adapter to drive a 1" copper pipe with a 1/2" drill bit… and the bushing to act as alignment guide and low friction bearing to the 4" horizontal bore.
You can see I made the driving adapter with a drafted set of ridges to match the fluting of the drill bit- 1 turn in 2"-
and it has radial ridges that are just .5 mm larger in diameter than the inside diameter of the copper pipe, with a taper at one end to allow the driver parts- when wrapped around the drill bit- to self center- and literally carve a quarter mm off all the splines as its force fit into the copper tube.
The drill can drive into the adapter- but only to the end of the fluting on the bit… where it locks like a thread and can not slip.
and this is them in action.
the bushing is in two parts so that it can be put around the copper pipe even when its already fed thru the hole in the plywood- its keyed for alignment, and fits the tube with only about 0.05mm play- the outside diameter of the bushing throat is about 0.03 larger than the hole in the plywood frame so the bushing force fits and does not spin relative to the shaft of the copper tube.
The ribs and flanges on one side of the bushing are to give it a longer aligned bearing surface, to make sure its axis stays perpendicular to the wooden frame section, and to provide a robust means by which we can yank the bushing out of the wood to use it in drilling another bore hole.
keep in mind, this copper tube is not perfectly round… and that it not only SPINS inside the bushing… but that it drives its length thru the bushing like a piston at the same time.
The ridges on the drive adapter allows for easier force fitting inside the copper pipe and resists slipping in the direction of rotation thru the multiple long ridge edges perpendicular to the rotational force. In trying to slip, the ridges will bend slightly, causing their trailing edges to bite more firmly against the inside wall of the tube…
I can readily pull the adapter out of the tube- the narrow ridges offer lower friction in that direction- but it will not turn when inside the tube- or- at least, the drag on the cutting head and 4 feet of copper shaft inside the urethane foam we are drilling is not enough to overcome the ridges’ grip inside the tube.
We spray just a bit of silicone lubricant on the tube for each bore… and there are some noticable markings inside the bushing from use… however, it has not gotten measurably looser as yet. And it holds that 4 foot long shaft dead true as it spins. So true that even tho spinning at 500 rpm- the tube looks stock still in the pictures.
so you see- we are using tough resin BOTH for a lower friction bearing… AND for a high friction driver in the same project.
Tough resin impresses. You simply have to design around its limitations.
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duplicate
This is really great - combining resins is a technique I use a fair amount. There are some examples in this post that combine Tough and Durable Resin (basically using Durable wherever I want lower friction / expect more cycling, like the bushings on the drill jig). Replacing Machined Jigs and Fixtures With 3D Printed Parts
If it’s combining Tough and Durable I usually use an annular snap fit (just a half circle revolve in a groove, 0.035" for the diameter, and 0.04" for the groove diameter. Pops in with hand pressure on flat surface and stays in quite nicely:
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Durable has the lowest friction coefficient so I would start with that. If the part is thick enough then it would be plenty structural also, just depends on your application. Of course if you can put a piece of Delrin on the contact surface, that is best.