Highly stretchy fabrics for machine tool way covers - Page 1
Forum section: electronics / general

author: Infraviolet
author_rank: Super Contributor
timestamp: October 05, 2025, 09:50:16 pm
content: I'm working on the design of a DIY CNC machineIt's in the early phases but a major element of the design will be "sealing" up the working volume so that the CNC won't spray little chips of freshly cut aluminium (it will be a CNC for routering/milling aluminium workpieces) either in to the room, or in to its own ballscrews/rails...I know the usualy solution is concertina folded way covers, which fold up as they contract... But as far as I can tell there is always the risk that these could bunch up in such a way as to push "down" in to the moving parts below and jam something such that the machine may damage itself, or bunch up and have some of the folds of the covers sliced open by the spindle tool.I was thinking of anactual elastic fabricfor the purpose instead, this way it would still be (just about) in some amount of tensions when at the relaxed end of travel, and under full tension when fully extended. This would mean it would never fold itself up or down, simplystay taught and close to flatwhen stretched and with things sized such that it would be just about under a tiny bit of taught tension when at minimum stretch.For the sizes I'm expecting I'd be looking at something stretching (in an X and Y dimension at the same time) to about 5 to 6 times the contracted default length (that is to say a stretch of 5 to 6 times on each of X and Y at the same time). Apparently in fabric terms this is known as a "4 way stretch".Now I know nylon filaments can stretch to something like 8 times their default contracted length, but any nylon fabrics I see for sale sound like they've been blended with other fibres which means they'll only stretch to 1.5 to 2 times their default size.I don't expect the aluminium chips to necesarily be hot, but they'll obviously be the sort of thing which can fairly abrasive if a piece of fabric gets rubbed back and forth against them a lot. So the ideal fabric would be somewhat hard wearing too. The fabric does not need to be liquid-proof, I don't mind if liquid drops of any cutting fluids or lubricant oils somehow got from the right side to the wrong side, just so long as the aluminium chips/dust/swarf stays on the side it should be on.Any ideas if a sufficiently stretchy fabric type exists? Oddly enough one of the closest things I found was some rubber sheeting from RS components, but this would be a bit of the heavy side, and still only got up to about a 3x stretch.Thanks

author: coppercone2
author_rank: Super Contributor
timestamp: October 06, 2025, 06:15:06 am
content: fabric is gonna be the thing that goes crazy if it gets up into something. I thought the more professional tools had a metal spring bellows like thing under neath the rubber to ensure it stays in roughly the correct shape.Metal bellows are very serious engineering objects BTW, that are available down to hermetic. But I just mean some spring steel ? thing that keeps it fluffed upAnd even bare rubber should not get caught up in any mechanism so long its thick enough to clearly not fit in any groovesFabric does all sorts of weird stuff like fraying, and in that state it can pretty much enter anything. Then yank a whole bunch more of it in there , and suddenly get pretty tough when its compressed and

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 06, 2025, 04:23:13 pm
content: Stretchy fabric has a maximum "stretch ratio" of around 1:4 and that is very likely not enough. And when you stretch it that much, it's also going to get narrower in the center, and under such a high load it's also likely to tear pretty soon.And that is not even considering the extra variable load on the axis of your machine.

author: coppercone2
author_rank: Super Contributor
timestamp: October 06, 2025, 05:02:47 pm
content: and the ultra fine particles will get into the fabric and slowly destroy it when it stretchesalso its going to get oil soaked, eventually, even if you cut dry, because of residual oils on the stock you are cuttingI just washed the fabric headband for my welding helmet. No, it was not clean, not at all.

author: thm_w
author_rank: Super Contributor
timestamp: October 06, 2025, 08:50:12 pm
content: https://hebeitonex.en.made-in-china.com/product/WFztdKUCADGr/China-High-Quality-Protective-Armor-Bellow-Cover-Stainless-Steel-Telescopic-Bellows-Covers-for-CNC-Machine.htmlhttp://cable-chains.com/Virgin-Islands-British/Machine-Tool-Guide-Way-Protection-Steel-Telescopic-Slideway-Cover.html

author: TimFox
author_rank: Super Contributor
timestamp: October 06, 2025, 09:33:23 pm
content: Before retirement, when we used precision linear bearing systems with lead screws in x-ray imaging systems, we covered the mechanism with a planar bellows, similar to the material in a bellows camera.However, those systems did not create swarf and debris like a machine tool will.

author: coppercone2
author_rank: Super Contributor
timestamp: October 06, 2025, 09:52:29 pm
content: does no one think that the concerns about rubber getting sucked into the machine ways are not valid?? I can't see this happening, but I don't know if it can.

author: Infraviolet
author_rank: Super Contributor
timestamp: October 13, 2025, 07:27:49 pm
content: Thanks for the thoughts about the risks of using fabric, and the alternatives. I'm not sure that those styles of way covers really fit to my design though. So I've included a diagram to show my situation a bit better. I've got a 20cmx20cm (dark grey) plate which can move around within a 40cmx40cm area (area bounded by the dashed line), outside that I've got a further 5cm of perimeter space in to which the cover can be compressed when the plate is at any of the extremes of its motion range. In effect this is a "seal" (not against liquid, but against small swarf particles, IP6X style) for a 2d motion, rather than a cover for a single axis. A seal of this kind would be much better than trying to defend various axes from chip entry individually, because this gives in effect one big area which can be cleaned off every so often rather than having to clean within gaps between movable parts.Any thoughts of what sort of thing I might DIY, or cheaply buy, for this application?Thanks

author: coppercone2
author_rank: Super Contributor
timestamp: October 13, 2025, 09:04:18 pm
content: can you just put sloped plates under neath into like a chip collector, like a roof and gutter? If its tall enough. You would just need some rubber on the very middle. That way you can even have it move to the extremes so the slope gets high and the chips want to fall, like a cleaning routine, it would pivot to follow the center

author: jpanhalt
author_rank: Super Contributor
timestamp: October 13, 2025, 09:29:41 pm
content: Some types of wonen's stockings have a high stretch ratio. Google AI:QuoteThat said, my mill has accordion like way covers. They work, but are hard to clean because of the crevices. I am skeptical of your approach using a fabric for the same reason. I have never had a problem with "bunching up," but then, the leadscrews are not exposed at all. Sliding plates with rubber seals may work better.

author: Infraviolet
author_rank: Super Contributor
timestamp: October 14, 2025, 07:05:40 pm
content: coppercone2: I don't think a "slanted roof" design would work, that would rely on having a "roof" wide enough to cover the full area even when the bed is over in one corner, but the whole idea is that nothing ever goes outside the 50cmx50cm outer square (because outside of that are vertical beams and such), and such solid sloped design would always end up outside the permitted area, in one direction, when at an axis limit.jpanhalt: That elastane stretch figure is for the fibres, I think, I'm not aware if anywhere actually sells pieces of pure elastane fabric, I think most elastane sold in bulk, as well as garments, are blended with other fibre types which means the stretch ends up more like 200% max. Given the ealier discussions though, I can see the undesirability of a fabric solution given the risk of a thread of the fabric getting in to moving parts then unravelling everything. ... Good to know I'm not alone though in hoping for a much more easily cleanable solution than separate way covers on each axis with crevices for chips to get stuck in.Is there perhaps some key word or phrase which would let me find examples online of this sort of 2 dimensional seal I am trying to create? Way cover related searches always bring up things designed to protect one axis at a time. Is there some other term I should be using to bring up things more related to my idea of covering up a square area?I'm also unsure as to quite what type of folding would be needed for covering a 2 dimensional area with the equivalent of a bellows-style concertina cover. This would remove the need for stretching, I could use rubber sheeting or something, but I would need some sort of fold pattern a bit like the shape of early cameras, but without needing so much length along the axis. Some fold pattern, perhaps with rigid elements glued on to some parts of the sheeting so as to control which points bending could occur at, which would be like a camera bellows, but much "shorter" (10 to 15cm maximum for the size I need) along what, for a camera, would be the focal axis. Any ideas of keywords for finding examples of such folded shapes?Thanks

author: jpanhalt
author_rank: Super Contributor
timestamp: October 14, 2025, 07:35:40 pm
content: "Sliding plate " was the wrong word. I suspect the correct search term is "telescoping way covers"https://hennigworldwide.com/telescopic-steel-covers.In theory, you could get almost any reasonable expansion ratio. From a practical standpoint, I suspect 6 to 8 telescoping pieces is about maximum. You could probably make something workable with a sheet metal brake and mill to give a Z-structure like the attached.

author: thm_w
author_rank: Super Contributor
timestamp: October 14, 2025, 09:14:34 pm
content: The diagram doesn't really help, I assume its a regular XY machine bed.This would work but you'd need 4 of them, and it still wouldn't provide full coverage. Can't think of anything simple that would do that. Usually people will put the mill in an enclosure and have a chip tray at the bottom.

author: jpanhalt
author_rank: Super Contributor
timestamp: October 14, 2025, 10:28:55 pm
content: Have you ever machined anything? What happens with a roll when it moves toward the chuck? You Tube intelligence on full display.BTW: Back and forth on a lathe bed relative to the chuck is the Z axis.

author: coppercone2
author_rank: Super Contributor
timestamp: October 14, 2025, 10:54:33 pm
content: Ok this is a guaranteed headache, use it as a interview question for google. The "get this ass out of the office" question.BTW I read some thing a while back about 100% of friction areas being hermetically sealed in some soviet graphite machining equipment. Maybe they have some insight some where if you look for a while

author: thm_w
author_rank: Super Contributor
timestamp: October 15, 2025, 12:09:36 am
content: Quote from: jpanhalt on October 14, 2025, 10:28:55 pmNot sure what you mean, OP wanted to use fabric for some reason, thats a fabric design. Though not cheap or simple.

author: coppercone2
author_rank: Super Contributor
timestamp: October 15, 2025, 01:27:26 am
content: I still think that the crux of any fabric material is just permeability. It will get grease from the chips. Unless you machine dry and wash all the work, it will get soiled.And then you have a big oily rag, which would burn excellent.IDK if you can get someone to wash a machine. I never saw it happen. Scrape, blow out, etc. But wash??Every shop rag I ever found had... self supporting properties. If its in a shop long enough it just seems to get greasy.IMO always design a machine with the "20 years in Chinese shop" mentality. Imagine it with most of the paint gone, giant grime stains, large amount of rusts, deep gouge marks, etc. The only thing that is going to look remotely clean is the friction surface. If you see a tool in service in that condition then you provide a good value IMO.5 million dollar eye sore. I noticed even the expensive CNC machines start to look like this in a 'productive' environment. I am suspicious if some of these things got cleaned, your co workers would call the cops and they would bring in a forensics team to look for signs of a murder LOL

author: Infraviolet
author_rank: Super Contributor
timestamp: October 15, 2025, 05:21:49 pm
content: I have discovered some of those magic search terms:X-Y ShieldorX-Y modular shieldbring up various images of a 2 dimensional sealing system.Very fancy, and big, and pricey, designed for huge machines. The question is now whether I can work out a way to DIY an equivalent. Concertina pieces for each section (you'd need 4 of them for an X-Y shield) are widely and cheaply available, the tough part is working out how you make a seal along the side of each concertina piece.The alternative is I start with a 70cm x 70cm * piece of toughened tarpaulin, I cut out the 20cm x 20cm hole in the middle. The edges I then bunch up to fit the 50cm x 50cm outer area. The I would have to work out a way of keeping whatever folding occurs within the material sheet manageable.* this size ensures that when the CNC's bed plate is at a limit on one axis, you've still got 25cm worth of material between the edge of the bed plate and the edge of the 50cm area. This 25cm worth of material ofcourse then bunches up somehow when the bed plate is centred or at the close (5cm from edge) extreme. 70cm gets this to work both ways round, when the bed is at a limit one side will be almost flat and stretched to 25cm, the other side will be compressed to 5cm and bunching up, somehow.