Square plastic tube plug model?

Spork,

At Heyco UK, you can get some details on the 25mm square hole plugs.

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Sporkman wrote:

One more thing: it would be good to get a prototype tool made if possible, so that you can adjust the parts to get the pull-out force that you need before you commit to a lot of cavities in a real tool.

Sporkman wrote:

Those guys at 8020.net who sell the extrusion components have plain square tubing, perhaps they have suitable plug dims.

Nyuk Nyuk Nyuk

Thank you, sir (and also thanks to Paul S.). I found the kind of part I'm looking for on Rodon's site, although once again as with McMaster-Carr there's no useful dimensional data. Can't find National Molding in Long Island at all, even though I found an article referencing their CEO. I guess I'll just "fake it" for now. Regardless, I doubt if we want to be creating a custom part.

Of course if I DID want to get a custom part made I would take your advice and create a rapid prototype. In case anyone has the need I've been getting automatic quotes from Quickparts.com for durable SLS parts that really blow me away. Fast, cheap AND good -- that's amazing. Ya send 'em STL files and the quote comes back in about 15 seconds. It's obvious that the quote machine takes into consideration that they can create multiple parts on the table at one time, and they discount accordingly because of the machine time saved. Among other things, ya can get nylon and glass-filled nylon and ABS models made CHEAPLY. Parts are made in 2 to 3 days and shipped standard overnight for the quoted cost. Damn! These people have it down to a fine science.

Mark 'Sporky' Staplet>

Browse this site Mark. Might be able to help.

Mt. Olive, NC

Thanks also Devon and 3 Stooges. I hadn't thought of 8020. From what I found so far there it looks like the end caps they have are intended for their standard structural extrusions, not simple square tubing, but I'll look at some other similar sites. Can't afford to use the typical kinds of extrusions sold by 8020 or Item or Bosch, etc., not only from a cost standpoint, but also from a weight standpoint. I'm working on a cheap consumer product, not a machine structure. Appreciate your time and thought regardless.

'Sporky'

Interesting site, regardless, Jimmy. Thanks. I'll bookmark this one, as I often get into machine design and such.

'Sporky'

Jimmy wrote:

So.. looking again,.. wouldn't the SQR-1-10-14 from Caplugs work?

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Sporkman wrote:

GREAT, Paul. I had looked through Caplugs twice (the 2nd time on your recommendation) and didn't find that. But no, unfortunately I don't believe the parts listed there will work. I've got a 1/8" wall on the tubing I'm using -- quite on purpose. I need to form some threads through one side of the tubing, and 1/16" just isn't enough thread depth for the application. Thus the inside square dimension in the tubing is .75 and the smallest rib dimension on the plugs intended for 1" tubing is .871. Appreciate very much your checking it out for me though. As always you're a gentleman.

'Sporky'

Paul Salvador wrote:

FWIW, my experience with these types of plugs has convinced me that any more than some nominal interference fit doesn't work well at all. The interference with the part you (Paul) pointed out is almost 1/16" on a side and that much almost certainly will be a PIB at best. Half that much interference fit might work pretty well. The companies that sell these things (like Caplugs) often greatly exaggerate the range of internal dimensions their parts will fit with, and I suspect that's so they don't have to have as many molds and stock as many different sizes.

Marky 'Sporky' Staplet>

Here is where we get all of our plugs. It seems to me that the finned caps do seem to work with many wall thicknesses, but these guys will send you free samples of most items like that.

Wow, now that site has a lot of different & unique *stuff* on it. I'll bookmark that one for later use as well. Thanks for that link, Devon.

'Sporky'

Dev>

Sporky,

You say you need to thread one wall, and this is the reason for going with the thicker wall tube. Have you considered flowdrilling?

We do a lot of this at my company when we need to attach something to thin-wall tube. Basically it's friction-drilling. It uses a special "drill-bit" in any standard commercial grade drill press (hand drills won't work), and deforms the material of the hole instead of cutting it. What you have after drilling the hole is cone of material that is draw down into the hole, which creates enough material thickness to allow you to thread more material than the what you started with. We've been flowdrilling at my comapny for a few years now, with little problem. We usually use HPRO & CRS

1020 tubing, as well as AISI 304 without any trouble.

It's just something to consider if you are having trouble finding the proper caps you are looking for.

Ray Los Angeles, CA

Now THAT's a nice machining process to know about regardless. Makes ya wonder whether the melted area becomes annealed in many instances, however, which of course would reduce the thread strength possibly even to a severe extent. I imagine that is addressed somehow, but it's not clear how. Unfortunately I can't use it 'cause I can't afford a boss on the outside, although one inside would be fine. I'll remember it, though. Thanks for the link, Ray. Learn sumpin' new every day!!

'Sporky'

Ray Reynolds wrote:

You can get a flowdrill that does not leave a boss on the OD of the tube being drilled.

Either way, good luck on your hunt for a cap plug.

The issue of the boss on the outside is a function of the speed, timing & plunge. I have a sample that I got at IMTS that shows both ways. When I watched the process, it was easier to visualize how it all works together.

WT