Press fit question

Hi. I make a product (http://basscapos.com/robpin.html ) which uses lengths of SS hot formed tube 10mm OD x 8mm ID. Some customers want a press in, har
dened point on the end of one of the tubes.
http://i389.photobucket.com/albums/oo340/robobass/Points_zps8uuji8py.png The design wants the tubes to be interchangeable, so ideally the point shou ld be both installable and removable by the customer, who presumably has no metalworking skills or tools. Maybe this simply isn't possible. Right now we're making it with a straight shaft 8mm long, with a tapered en d. Problem is that the tube is not all that consistent for either roundness or ID, so naturally some points fit nicely, while others don't work at all . Besides changing to a more dimensionally consistent tubing, is there a tw eak which would make the point more universal? Maybe a very slight taper in stead of a straight shaft? Thanks
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On Tuesday, July 11, 2017 at 10:27:57 AM UTC-4, robobass wrote: Problem is that the tube is not all that consistent for either roundness or ID,

Many years ago I visited a place that made tubing. They pulled a piece thru tubing to increase the id . So the ID was very uniform and round. As I remember they used hydraulics .
Dan
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On Tue, 11 Jul 2017 08:38:06 -0700 (PDT), " snipped-for-privacy@krl.org"

Mandrel forming - works better on larger tubes.
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On 7/11/2017 11:38 AM, snipped-for-privacy@krl.org wrote:

You can get better SS tube cheaper at "Trent Tube" in Wisconsin. Just mention my name, my sister Pat was VP sales for many years.
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On Thursday, July 13, 2017 at 9:20:01 AM UTC+2, Tom Gardner wrote:

I should have mentioned that I am in Germany! both of the types I've mentioned in 10mm x 1mm tube cost me about eight bucks per meter, so price isn't a big issue for this project.
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Hi. I make a product (http://basscapos.com/robpin.html ) which uses lengths of SS hot formed tube 10mm OD x 8mm ID. Some customers want a press in, hardened point on the end of one of the tubes.
http://i389.photobucket.com/albums/oo340/robobass/Points_zps8uuji8py.png The design wants the tubes to be interchangeable, so ideally the point should be both installable and removable by the customer, who presumably has no metalworking skills or tools. Maybe this simply isn't possible.
Right now we're making it with a straight shaft 8mm long, with a tapered end. Problem is that the tube is not all that consistent for either roundness or ID, so naturally some points fit nicely, while others don't work at all. Besides changing to a more dimensionally consistent tubing, is there a tweak which would make the point more universal? Maybe a very slight taper instead of a straight shaft? Thanks ======== How about an O ring instead of metal-to-metal friction?
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On Tue, 11 Jul 2017 07:27:51 -0700 (PDT), robobass

The easiest thing probably would be to go to a DOM tubing (if it's available in the SS you're using) That stuff, in carbon steels, typically is +0.000, -0.003 in. or so in small diameters like that. But I don't know about SS.
Aside from that, a complicated solution is an expanding-mandrel approach for the point. Not a very good solution.
A simpler one would be to size the ID of the tube with a reamer or a diamond hone (Sunnen's diamond hones are very good for accurate sizing. You can run one in a drill press.)
That is, if you have enough wall thickness to deal with the range of inaccuracies you have to deal with.
If you press-fit it, it will have to be very accurate for someone with no metalworking knowledge to replace them. You might want to get the sizing close, and then turn two grooves on the point that you fit with neoprene O-rings. Depending on how inaccurate your tube is, that might even allow you to skip the sizing step.
Good luck!
--
Ed Huntress

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On 7/11/2017 10:06 AM, Ed Huntress wrote:

I suggest you use more Astro-glide.
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On Tuesday, July 11, 2017 at 6:07:09 PM UTC+2, Ed Huntress wrote:

hs of SS hot formed tube 10mm OD x 8mm ID. Some customers want a press in, hardened point on the end of one of the tubes.

hould be both installable and removable by the customer, who presumably has no metalworking skills or tools. Maybe this simply isn't possible.

end. Problem is that the tube is not all that consistent for either roundn ess or ID, so naturally some points fit nicely, while others don't work at all. Besides changing to a more dimensionally consistent tubing, is there a tweak which would make the point more universal? Maybe a very slight taper instead of a straight shaft?

Actually, O-Rings are sounding better and better as I think about it more.
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On Tue, 11 Jul 2017 07:27:51 -0700 (PDT), robobass

Consider a threaded in point?
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On 7/11/2017 7:27 AM, robobass wrote:

Isn't gouging a hole in the floor of the venue a bad idea?
Make threaded insert and thread the pointy thing.
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etter yet, supply an extra "tube" with the pin permanently attached - or put the pin in the opposite end from the rubber tip - simply flip the pin.
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Thanks everyone. The reamer idea sounds like the ticket. Don't know why we didn't think of it... Threads are lots of work, and they get loose and ratt le. I can also get seamless St35Bk non-stainless for just a little bit more money, which is way more dimensional. Thinking about it, but stainless is already in all of the press stuff, so if I change to carbon steel then cust omers might think I'm cheating. Marking the floor? Good question. Many bass ists and cellists prefer a point, both for stability, and some say better s ound. Some stages allow it, some strictly forbid it! The reason I can't ins ert the point myself is that since the rods are interchangeable, there is n o way to know which rod will get the point until after the player has exper imented a bit. I suppose that if I make it so the player can hammer it on h imself, but won't be able to remove it, then that should be good enough.
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Thanks everyone. The reamer idea sounds like the ticket. Don't know why we didn't think of it... Threads are lots of work, and they get loose and rattle. I can also get seamless St35Bk non-stainless for just a little bit more money, which is way more dimensional. Thinking about it, but stainless is already in all of the press stuff, so if I change to carbon steel then customers might think I'm cheating. Marking the floor? Good question. Many bassists and cellists prefer a point, both for stability, and some say better sound. Some stages allow it, some strictly forbid it! The reason I can't insert the point myself is that since the rods are interchangeable, there is no way to know which rod will get the point until after the player has experimented a bit. I suppose that if I make it so the player can hammer it on himself, but won't be able to remove it, then that should be good enough.
======================= These used to be allowed to fasten down scenery: http://www.bullworks.net/daily/20070729.htm
However raising splinters in the stage floor with them was said to be a good way to discover how hard a dancer can kick. -jsw
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robobass wrote:

How about taking a page from camera monopods and walking sticks. You machine a screw into a point that can be press fit into the end of the tube, then add a rubber foot that can be screwed up to reveal the point or down to have a rubber foot. Making a retractable point foot.
Like
https://cdn.photographylife.com/wp-content/uploads/2010/04/Gitzo-Tripod-Feet.jpg
or ebay item 171751891766
or google Gitzo GS5030VSF Rubber Feet, Spike Tip
Gives the best of both worlds and can be sold as a "product accessory"
--
Steve W.

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Cool idea, but with the size constraint it would be way to delicate.
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On 7/11/2017 10:27 AM, robobass wrote:

How about epoxying a neodymium magnet into the tube to hold the tip?
Like these:
https://www.apexmagnets.com/8mm-x-8mm-cylinder?fee=5&fep77&gclid=CLrlqYKRhdUCFYi2wAodEJwD3Q
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I like this a lot, but I'd have to put one in each tube.
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