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  • sid pileski
    replied
    If your trying to obtain higher precision, that’s not the way.
    Plus if your after a .156 finished slot width, starting with a .156 endmill in a chuck won’t get you there...

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  • J Tiers
    replied
    Originally posted by sid pileski View Post
    Ahhhhh!!!

    An endmill in a drill chuck! Come on,I know you have collets for your mill!!
    Pfui....

    I've done that too, and it works OK, even if I don't like doing it. I've done it because if I use the EM in the MT3 horizontal spindle, I have no MT3 holder for 0.187" shank end mills, and only have MT2 collets in that size. Adapters of course block the drawbar, and I do have an MT3 shank on a drill chuck for the mill (and an MT2 as well).

    Lightning does not strike, it's OK.. ... Brian does such nice work that I'd never quibble on that sort of thing.....

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  • sid pileski
    replied
    Ahhhhh!!!

    An endmill in a drill chuck! Come on,I know you have collets for your mill!!

    Leave a comment:


  • bob_s
    replied
    No need for any dis-assembly, being a spray lube, you could have the engine self ingest the lubricant by injecting in the steam chests until a drop formed in the exhaust port.
    Silicone acts like micro-ball bearings between any sliding surfaces.

    Leave a comment:


  • brian Rupnow
    replied
    Originally posted by bob_s View Post
    Have you tried spray silicone lubricant with your viton o-rings?
    No I haven't tried that. The ring is totally encased in a cylinder.

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  • bob_s
    replied
    Have you tried spray silicone lubricant with your viton o-rings?

    Leave a comment:


  • brian Rupnow
    replied
    In hindsight, I wish now that I had put both plates on my fixture and machined them both a once. Since I can only take about 0.010" depth of cut for fear of breaking my 0.156 endmill, it wouldn't have been a problem if I'd had both plates on there.---live and learn.

    Leave a comment:


  • brian Rupnow
    replied
    This is as much as I'm going to do today. There is more that I can chew away before tearing down this set-up, but this is as far as it's going today.

    Leave a comment:


  • brian Rupnow
    replied
    Second radial cut. Not as much breath holding this time, as I was able to use a 3/8" endmill. I'm running the mill at about 900 rpm, and cranking the rotary table slowly, cutting in both clockwise and counterclockwise direction. I advance the tool 0.010" each time I get to the end of a rotation. In a way part of this is climb milling, but a great deal more of the cut is endmilling.

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  • brian Rupnow
    replied
    One picture of set-up and one of main slot milled. Lots and lots of breath holding and butt clenching going on!!!

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  • Baz
    replied
    String - how century before last. Square section graphite.
    You did give the o-ring rolling room ?

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  • brian Rupnow
    replied
    McGyver--I have a bad history with cast iron rings. I've tried to make them about four times, and after four failures said "Screw it!!!" As far as the depth and width of grooves for a 1/16" cross section o-ring---0.093" is fine for width (and also happens to be the width of my parting off tool). The depth of cut is also what determines the amount of "squash" on the ring when you fit the piston into the cylinder. On all of my i.c. engines, I made the grooves 0.057" deep. On this one I made the groove depth 0.060" deep. Note that a 1/16" o-ring is actually 0.070" in cross section.

    Leave a comment:


  • Mcgyver
    replied
    the way an O ring seals isn't (at least wasn't for) me intuitive. Its not outward pressure or a tight squeeze between cylinder and bottom of groove, its how it bunches up. Its an engineered thing, the size of the groove, and there is suppose to be some play in the width and its the ring bunching up at one end of the groove that provides the sealing. if you google it, there is all kinds of good information from manufacturers on sizing the groove. Kind of like to get the seal you need to do X, and the drag will be what it will be.

    Why not iron rings? There's nothing in making them you wouldn't be able to do.

    Leave a comment:


  • brian Rupnow
    replied
    Sid--You are very probably right. If I find that I can't live with the Viton, I will try the oiled string.---Brian

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  • sid pileski
    replied
    Most times, with the steam engines I've built, I use a good fit piston to cylinder (.001-002) under on piston. (on up to the 1.50 dia bore)
    Then I use cotton string as the packing. The groove is machined so that I get 3-4 wraps of the string. I'm using common .030-.040 Dia. cotton.
    The advantage is low drag, and it retains the oil, provides plenty of seal.
    I'd bet that you could replace the current O-ring with cotton, and see an improvement at low pressures, then you can retain your bragging rights, OD.

    Sid

    Leave a comment:

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