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  • brian Rupnow
    replied
    I have heard most of the conventional wisdom about two flute versus four flute, holding endmills in chucks, etcetera. I believe 99% of it, unless personal experience shows me something different. Some of the things I've heard, I haven't yet had the opportunity to verify.

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  • Sparky_NY
    replied
    Originally posted by brian Rupnow View Post
    For what it's worth---I cut the arced slot in the second part with my 0.156" four flute endmill held in a collet. The slot measures 0.161" wide. When I cut the slot in the first part with the same endmill held in a chuck, the slot came out at 0.165" wide.
    I have read many times that cutting a slot with a on-size endmill should be done with a 2 flute endmill because it will come out oversize otherwise.

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  • J Tiers
    replied
    They look good.

    I'm not surprised they are that close in size (0.161 vs 0.165). That is an off-center of a couple thou. Despite the dire comments, drill chucks of a decent make are rarely out very much, especially if they are ones made to take a range including small (1/16") drills.

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  • brian Rupnow
    replied
    And now there ate two. Not nearly as much drama with the second one.

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  • brian Rupnow
    replied
    For what it's worth---I cut the arced slot in the second part with my 0.156" four flute endmill held in a collet. The slot measures 0.161" wide. When I cut the slot in the first part with the same endmill held in a chuck, the slot came out at 0.165" wide.

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  • J Tiers
    replied
    Usually, it is not good to try to cut an on-size slot with an exact size end mill. It rarely works out as expected, although it is possible to get lucky.

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  • brian Rupnow
    replied
    So---we have one reversing link finished. All of the holes and centers of radii are exactly where they should be. The arc is exactly where it should be. Sid was right, cutting the 0.156" wide arc with a 0.156" endmill held in a drillchuck is not accurate---The slot ended up at 0.165" wide. This does not pose a problem for me, as I am the one who makes the "follower" that runs in the slot. When I do the second link, I will hold my 0.156" endmill in a collet and see if that yields anything different.

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  • brian Rupnow
    replied
    I have reached the limit of what I can do in my milling set-up. The remainder of material to be removed will be done with bandsaw and file.

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  • bob_s
    replied
    Originally posted by brian Rupnow View Post
    Bob_s--I may try that. I have a couple of spray cans of silicone for waterproofing leather coats. I wonder if that would work?
    I think that stuff is more of a sealant like clear RTF than a lubricant.

    The stuff that I'm using is marketed by the makers of WD40/3in1.

    Test it by taking an o-ring and a piece of scrap aluminum sheet, spray and allow to dry. Then check to see if the o-ring is stuck or not.

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  • danlb
    replied
    Just as a side note;

    Brian said "Lots and lots of breath holding and butt clenching going on!!!"

    and Sid said "Ahhhhh!!! An endmill in a drill chuck!"


    The two are related. A drill chuck will often have a lot of run-out. A lot of run-out combined with a small end mill results in more wear and stress as the mill essentially acts like it's doing an interrupted cut. Some say you effectively end up with a single tooth cutter as the mill follows an eccentric (???) path.

    There should be less pucker factor if you simply change to a collet.

    Dan

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  • 10KPete
    replied
    Originally posted by brian Rupnow View Post
    ..... I am the one who makes the roller that rolls in that slot, and I can make it to whatever the slot ends up as...;...
    And that is THE thing to keep in mind in this hobby! We're not making a load of interchangeable parts. All we have to do is match two parts together...

    Dimensions on a print can usually be considered "guides".

    I love hand made....

    Pete

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  • sid pileski
    replied
    Originally posted by brian Rupnow View Post
    I do it all the time. I get away with it most times because the endmills are small. I do have proper collets for my larger endmills.
    Have you ever checked the run out?

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  • brian Rupnow
    replied
    Originally posted by sid pileski View Post
    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...
    Sid--I knew that, or at least "in theory" I knew that. I could have started out with a 1/8" endmill and then offset it to reach the 0.156" measurement. Conventional knowledge seems to be that I wouldn't end up with an exact 0.156" slot even if the cutter was held in a collet. However, all is not lost. There's a trick. I am the one who makes the roller that rolls in that slot, and I can make it to whatever the slot ends up as.--I just checked the slot width with a Vernier caliper and it measures about 0.160" but it's still in the set-up and rather difficult to measure at the moment.

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  • brian Rupnow
    replied
    Bob_s--I may try that. I have a couple of spray cans of silicone for waterproofing leather coats. I wonder if that would work?

    Leave a comment:


  • brian Rupnow
    replied
    I do it all the time. I get away with it most times because the endmills are small. I do have proper collets for my larger endmills.

    Leave a comment:

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