Drilling deep in delrin
Close
Login to Your Account
Page 1 of 2 12 LastLast
Results 1 to 20 of 24
  1. #1
    Join Date
    Nov 2018
    Country
    UNITED STATES
    State/Province
    Utah
    Posts
    4
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default Drilling deep in delrin

    Hello

    I have a job coming up that involves drilling a 7/8 inch hole about 9” deep in delrin on a engine lathe. The last company that did this wound up shattering the delrin while drilling and blowing a hole through the ceiling of his shop. He said that the drill grabs the material too aggressively and gets sucked in. I was not able to get any more details on his set up. While drilling some simple parts on a drill press I had it bite so hard it sucked the part and the vice up off the table. I found that using a spade bit for wood from the hardware store worked very well and did not grab the material like a twist drill did.

    I want to avoid all of these problems. Can you recommend a drill for this 7/8” hole 9” deep? Do I need to re grind the drill? I can drill from both ends but would prefer doing it in one shot.

    Thanks

  2. #2
    Join Date
    May 2011
    Country
    UNITED STATES
    State/Province
    New Jersey
    Posts
    1,920
    Post Thanks / Like
    Likes (Given)
    173
    Likes (Received)
    1042

    Default

    Not sure what the hell that guy was doing but...you can pretty much ram a drill through delrin as fast as you can feed it. Throw some coolant at it and clear the chips here and there. I would say I'm amazed but I'd be lying.

  3. Likes Mtndew, Booze Daily liked this post
  4. #3
    Join Date
    May 2004
    Location
    Ridgefield, Wa USA
    Posts
    561
    Post Thanks / Like
    Likes (Given)
    190
    Likes (Received)
    70

    Default

    Onsrud makes drill bits for plastic I have used them on UHMW they work really good but not 9" deep the flutes only go in about 4" once you pack the bit it is going to stick and pull the part out of the chuck or you will have to peck it to death. I would use the spade bit and a vacuum to suck the chips that works pretty good just break the string every so often.

  5. #4
    Join Date
    Jan 2003
    Location
    Canada
    Posts
    11,175
    Post Thanks / Like
    Likes (Given)
    5214
    Likes (Received)
    3315

    Default

    Don't pilot, always drill to size right away. I use regular HSS twist drills. Probably need a long length one for that.

  6. Likes Bluejeep liked this post
  7. #5
    Join Date
    Aug 2006
    Location
    Cape Cod, Ma
    Posts
    452
    Post Thanks / Like
    Likes (Given)
    169
    Likes (Received)
    96

    Default

    my guess would be they were using a mt shank drill that was not seated well. deep holes in delrin are not a problem just don't drill past the flutes that's a recipe for melt. peck drill and some coolant or I like to liberally brush on some Acculube #10 perfect tap along the drill (which is a great general purpose cutting fluid). even some wax lube along the flutes help to keep the heat down. it's important to keep the heat down as the hole will shrink and grab.

  8. #6
    Join Date
    Jun 2012
    Location
    Michigan
    Posts
    4,574
    Post Thanks / Like
    Likes (Given)
    4181
    Likes (Received)
    2733

    Default

    Quote Originally Posted by CMacine View Post
    The last company that did this wound up shattering the delrin while drilling and blowing a hole through the ceiling of his shop.
    That sounds like a massive exaggeration or the other guy was drilling UHMW.
    I've never had a drill grab in Delrin. That is arguably the best material to machine on the planet.

  9. Likes Bobw, Ox, Bill in PA liked this post
  10. #7
    Join Date
    Mar 2009
    Country
    UNITED STATES
    State/Province
    California
    Posts
    4,888
    Post Thanks / Like
    Likes (Given)
    89
    Likes (Received)
    901

    Default

    A Forstner style bit. Probably will need a shank extension.

  11. #8
    Join Date
    Nov 2013
    Country
    UNITED STATES
    State/Province
    Utah
    Posts
    4,366
    Post Thanks / Like
    Likes (Given)
    1169
    Likes (Received)
    2395

    Default

    Quote Originally Posted by CMacine View Post
    Hello

    I have a job coming up that involves drilling a 7/8 inch hole about 9” deep in delrin on a engine lathe. The last company that did this wound up shattering the delrin while drilling and blowing a hole through the ceiling of his shop. He said that the drill grabs the material too aggressively and gets sucked in. I was not able to get any more details on his set up. While drilling some simple parts on a drill press I had it bite so hard it sucked the part and the vice up off the table. I found that using a spade bit for wood from the hardware store worked very well and did not grab the material like a twist drill did.

    I want to avoid all of these problems. Can you recommend a drill for this 7/8” hole 9” deep? Do I need to re grind the drill? I can drill from both ends but would prefer doing it in one shot.

    Thanks
    I kid you not, I'm being 100% serious. I think I've heard that story before, and might have worked for that moron. No names. He means well with his warnings, and has decent foresight for potential problems. But he always needs some catastrophic story to back him up, instead of just saying it. Solution has already been stated. To reiterate; coolant, no pilot, don't baby it.

    R

  12. #9
    Join Date
    Nov 2014
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    3,426
    Post Thanks / Like
    Likes (Given)
    1474
    Likes (Received)
    1618

    Default

    Lets see... I use a lot o "LoL and LMAO", but this has to be the first time in along time it was really true... (:


    blowing a hole through the ceiling of his shop.



    edit: was it the little piggy's shop made of straw?

    I'll huff and puff and bllloooowwwww the house down! hahahha

  13. #10
    Join Date
    Dec 2014
    Country
    CANADA
    State/Province
    British Columbia
    Posts
    1,275
    Post Thanks / Like
    Likes (Given)
    361
    Likes (Received)
    581

    Default

    If you're worried about the drill grabbing, brass the drill. Delrin won't care.

    I would not be adverse to drilling it half and half undersized and hitting it with a boring bar to pretty it up.

  14. Likes aj liked this post
  15. #11
    Join Date
    Feb 2005
    Location
    Hatch, NM Chile capital of the WORLD
    Posts
    9,018
    Post Thanks / Like
    Likes (Given)
    13662
    Likes (Received)
    10663

    Default

    Quote Originally Posted by Mtndew View Post
    That is arguably the best material to machine on the planet.
    Arguably?? Its a fact!!! All machined parts should be made from Delrin (or at least all
    the machined parts I have to make)..


    I've never had a drill grab in Delrin either. Its really mild mannered.. Its hard enough that
    you can hold it, its soft enough to cut easy, but hard enough that its not gummy like Teflon or
    UHMW . I've personally never experienced the grabbing and pulling with delrin that some
    of the other softer plastics are famous for.

    I was trying to open up a 5/16 hole to 3/8 the other day in Nylon, with a hand drill..
    Damn drill just screwed itself into the nylon.. Like a self tapping drill/screw?
    Delrin would never do that, its too well mannered.

  16. #12
    Join Date
    Nov 2013
    Country
    UNITED STATES
    State/Province
    Utah
    Posts
    4,366
    Post Thanks / Like
    Likes (Given)
    1169
    Likes (Received)
    2395

    Default

    Quote Originally Posted by Mike1974 View Post
    Lets see... I use a lot o "LoL and LMAO", but this has to be the first time in along time it was really true... (:


    blowing a hole through the ceiling of his shop.



    edit: was it the little piggy's shop made of straw?

    I'll huff and puff and bllloooowwwww the house down! hahahha
    Aside from just thinking about the process and facts--a part that is 9" long in a manual lathe chuck, with a 7/8" Drill inside of it, suddenly pulled out of the chuck, somehow escaped having a big ass Drill in it----THEN managed to fly upward with enough force to break a hole in the roof!!!!! Good God, WTF is going on?

    Meanwhile, back in reality-assuming the Drill did bite too deep, the part spun in the chuck. What else could realistically happen? The MT slipped maybe, but the fucking thing didn't drill itself a hole deep enough to let the whole Drill go.

    Even if the part somehow got away, if it had that much force it would break. Delrin isn't great for hard impact.

  17. #13
    Join Date
    Mar 2011
    Location
    Geneva Illinois USA
    Posts
    6,027
    Post Thanks / Like
    Likes (Given)
    2517
    Likes (Received)
    2337

    Default

    You want to make sure the margins aren't worn.

    Tom

  18. #14
    Join Date
    Sep 2010
    Location
    Vancouver Canada
    Posts
    884
    Post Thanks / Like
    Likes (Given)
    641
    Likes (Received)
    305

    Default

    Where I come from (research machine shops established by post-war European emigres where lightly used tools can hang around for a REALLY long time) they'd always have two sets of HSS drills, one for aluminum and steel with the normal cutting angle and one for brass and plastic with the cutting angle ground back to 90 degrees or so. I started a thread recently about the history of Delrin in prototyping because in physics anyway, Nylon and teflon were preferred for vacuum outgassing reasons so I'm not sure what the official old European guy view on Delrin is. So I would ask, would it still be better to use less acute cutting angle on Delrin if you happened to have such a drill, or is Delrin so good it really doesn't matter?

  19. #15
    Join Date
    Sep 2005
    Location
    Oakland, CA
    Posts
    2,421
    Post Thanks / Like
    Likes (Given)
    246
    Likes (Received)
    644

    Default

    If grabbing its an issue, just flatten the lips of the drill slightly and it won't dig in or grab. if you are getting a formaldehyde smell during machining, you are melting the resin- slow things down a bit and life will be good.

  20. #16
    Join Date
    Nov 2013
    Country
    UNITED STATES
    State/Province
    Utah
    Posts
    4,366
    Post Thanks / Like
    Likes (Given)
    1169
    Likes (Received)
    2395

    Default

    Call me crazy Dan. I've heard it before about the smell of formaldehyde, in relation to melting Delrin/Acetal. I have no idea what formaldehyde smells like! I don't hang out in the same places some as you guys, I guess. I'm trying to grasp why or under what circumstances, you people are smelling embalming fluid.

    R

    "This Chloraphorm smells funny to me, here you smell it and see if you think it smells weird too"

  21. #17
    Join Date
    Feb 2014
    Location
    Sunny South West Florida, USA
    Posts
    2,679
    Post Thanks / Like
    Likes (Given)
    10284
    Likes (Received)
    3107

    Default

    Quote Originally Posted by litlerob1 View Post
    Call me crazy Dan. I've heard it before about the smell of formaldehyde, in relation to melting Delrin/Acetal. I have no idea what formaldehyde smells like! I don't hang out in the same places some as you guys, I guess. I'm trying to grasp why or under what circumstances, you people are smelling embalming fluid.

    R

    "This Chloraphorm smells funny to me, here you smell it and see if you think it smells weird too"

    I've smelled the formaldehyde (You never dissected anything in school, Rob? We dissected cats for my AP Biology class my freshman year... They hung around for about 2 weeks before we finished... Yeah, I'll never forget what formaldehyde smells like...)... I also think it vaguely smells like the Crayola brand paints we used in art class when I was in elementary school.... Not sure why... Smell is a funny thing, it's really good at triggering long dormant memories...

  22. #18
    Join Date
    Nov 2013
    Country
    UNITED STATES
    State/Province
    Utah
    Posts
    4,366
    Post Thanks / Like
    Likes (Given)
    1169
    Likes (Received)
    2395

    Default

    Naw, I dropped out in the 6th grade, once I finished Elementary school.

    R

  23. Likes TeachMePlease, Mtndew liked this post
  24. #19
    Join Date
    Aug 2002
    Location
    West Unity, Ohio
    Posts
    25,073
    Post Thanks / Like
    Likes (Given)
    5312
    Likes (Received)
    7827

    Default

    Quote Originally Posted by CMacine View Post
    Hello

    I have a job coming up that involves drilling a 7/8 inch hole about 9” deep in delrin on a engine lathe. The last company that did this wound up shattering the delrin while drilling and blowing a hole through the ceiling of his shop. He said that the drill grabs the material too aggressively and gets sucked in. I was not able to get any more details on his set up. While drilling some simple parts on a drill press I had it bite so hard it sucked the part and the vice up off the table. I found that using a spade bit for wood from the hardware store worked very well and did not grab the material like a twist drill did.

    I want to avoid all of these problems. Can you recommend a drill for this 7/8” hole 9” deep? Do I need to re grind the drill? I can drill from both ends but would prefer doing it in one shot.

    Thanks

    Just in case of grabbing in a quill app, just keep some tension of the quill brake.

    This is the "CNC" board tho.



    --------------------

    Think Snow Eh!
    Ox

  25. #20
    Join Date
    Jan 2003
    Location
    Canada
    Posts
    11,175
    Post Thanks / Like
    Likes (Given)
    5214
    Likes (Received)
    3315

    Default

    I should add it can grab when it punches through the other side if feeding heavy, mostly with bigger drills. Moderate feed is usually good, too heavy can fracture it a little. PVC does that too.

  26. Likes Ox, litlerob1 liked this post

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •