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    End cap problem...

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    Tom(ADMIN)
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    End cap problem...

    Post  Tom(ADMIN) on Thu Dec 12, 2013 2:42 pm

    I ordered a pair of end caps from RC SubWorkshop in Hong Kong, and when they arrived they are a touch too big to fit the tube. Rather than send them half way around the world back to HK, is there a way that they can be altered to fit?

    I wondered about filing an angle on the tube end...is that feasible? It would be one hell of a job filing a chamfer by hand, but it may be possible?






    Richard
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    merriman
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    Re: End cap problem...

    Post  merriman on Thu Dec 12, 2013 6:52 pm

    Buying generic bulkheads for extruded tube (no mater the material) is a fools-errand. Not even cylinders cut from the same batch of extruded tube will match up.

    The industry standard for most versions of plastic tube/pipe/cylinder extrusions presents the manufacturer with a very wide tolerance as to internal and external diameters. Even the stated wall thickness of such product will vary from one lot to another.

    The only solution to this is to employ raw castings of the bulkhead that are sized to fit the upper end of the inner diameter tolerance for the specific size cylinder you would buy. It's up to the end-user to machine the flange (the internal face) of the bulkhead to a tight non-interference fit to the cylinder at hand.

    Consider yourself lucky, Richard. At least the bulkheads you have are oversize, and not undersized. Have that thing chucked up and turned to fit your specific cylinder. No sweat.

    David

    Tom(ADMIN)
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    Re: End cap problem...

    Post  Tom(ADMIN) on Thu Dec 12, 2013 8:04 pm

    Thanks for that, David...it's my own fault, I bought the tube from my usual eBay supplier, and ordered the end caps from Donald in HK...lesson learnt.

    I've sent the tube to MMB (a UK manufacturer of of sub parts) and they are going to make me up a set of end caps to suit the tube. Should have done that in the first place, shouldn't I?

    I'll ask around and see if someone can trim these other caps to fit as well, that way I'll have a spare set for something, they are always handy to have around.


    Richard
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    profesorul
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    Re: End cap problem...

    Post  profesorul on Thu Dec 12, 2013 8:37 pm

    Richard , did You send along with end caps the tube too ?.
    For them and for YOU also is much safer to have it ....as Mr MERRIMAN said :"a very wide tolerance as to internal and external diameters". My opinion.

    MARIUS

    Tom(ADMIN)
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    Re: End cap problem...

    Post  Tom(ADMIN) on Thu Dec 12, 2013 8:50 pm

    I didn't send the tube to Hong Kong, Marius...I should have done, I think. But to the other guy (MMB) then, yes...I sent him the tube and he will make the end caps to match the tube.


    Richard
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    david f
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    Re: End cap problem...

    Post  david f on Fri Dec 13, 2013 9:07 am

    Wise words from David, I would say.

    I even buy my "sewer pipe" in long lengths and store it in the shed! (A lot of variation in ID.)

    David

    Tom(ADMIN)
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    Re: End cap problem...

    Post  Tom(ADMIN) on Fri Dec 13, 2013 9:45 am

    It's surprising how the id of this stuff varies...the tube in the Dragonfish varies that much over a 400mm length, that one end cap won't fit the other end...and it's only 400mm away!



    Richard
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    merriman
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    Re: End cap problem...

    Post  merriman on Fri Dec 13, 2013 1:46 pm

    One of the production steps during manufacture of a Sub-Driver is to turn the bulkheads to fit a particular length of cylinder. The sloppy tolerance of extruded plastic tube/pipe/cylinder is the biggest drivers of SD expense -- the need to custom size bulkhead flanges to fit a particular cylinder.

    David

    Tom(ADMIN)
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    Re: End cap problem...

    Post  Tom(ADMIN) on Fri Dec 13, 2013 2:00 pm

    I can understand that, that's why I sent the tube off to MMB to have the end caps made to fit...properly. Must be a right pain in the proverbial...


    Richard
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    merriman
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    Re: End cap problem...

    Post  merriman on Fri Dec 13, 2013 4:05 pm

    Richard(Admin) wrote:I can understand that, that's why I sent the tube off to MMB to have the end caps made to fit...properly. Must be a right pain in the proverbial...


    Richard

    ... Indeed! Indeed it is.

    One reason the SD's cost so much.

    David

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