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  1. #1
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    hole drilling coolant question

    Hello,

    I have been using a 1" hole saw to make plates for my plate-style fork crowns. Doing this often will destroy the saw on a 3/16 or 1/4" plate, because the saw gets too hot. This hardens the steel as well.

    I'm trying to figure out the best way immerse the piece and the end of the saw in coolant. I'd like to keep mess down. This is in a drill press, and I generally use an arbor with a center drill to align the saw to the piece.

    I can't quite figure out a good solution but thought some of the clever people on this forum might have one.

    Thanks,
    Jim

  2. #2
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    For drilling in granite I've seen people build a putty dam around the hole and fill that with coolant.
    NOTHING WORKS LIKE CLOCKWORK

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  3. #3
    AZ
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    Garden sprayer and a catch pan.

  4. #4
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    Use cutting oil (or really any oil), slow your rpm's down, and use a nice heavy feed pressure. You have to get under the chip.

  5. #5
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    Joel, thanks. I was thinking along those lines, but there's nothing to keep the coolant from going through the center drill's hole. I could possibly remove the drill once I get the cut going, and plug the hole.

    Dirty $anchez, that's basically what I do now, but it does not deliver enough coolant, is messy, and takes a lot of spraying.

    Optimus, can you explain what you mean by "under the chip"?

  6. #6
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    Quote Originally Posted by JaquesN View Post
    Optimus, can you explain what you mean by "under the chip"?
    If you are spinning too fast, or not feeding heavy enough, you will "rub" your cutter and not cut effectively. This results in premature tool dulling, and work hardening of the material. Apply enough oil to keep the work area thoroughly coated, run your rpm's slow enough that you can almost see the individual teeth when it's spinning, and use a heavy enough feed that you peel a nice chip. Work hardening happens on the surface of the material, getting "under the chip" will keep your cutting happening below the surface and any potential work hardening. Spinning slower will lessen the heat generated by the cutter. You'll be wanting a chip approximately .002 thick. Slower rpm's, heavier feed, oil.

  7. #7
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    WD40 works great too if you don't have coolant and a pan to collect it.

  8. #8
    DWF
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    Don't use a hole saw, use a drill bit. Stack and clamp the parts and drill several at a time. For a 1" bit in 4130, start at around 250-rpm and maybe .015" feed per revolution.
    A man must have enemies and places he is not welcome. In the end we are not only defined by our friends but those against us.

  9. #9
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    Quote Originally Posted by DWF View Post
    Don't use a hole saw, use a drill bit. Stack and clamp the parts and drill several at a time. For a 1" bit in 4130, start at around 250-rpm and maybe .015" feed per revolution.
    Kinda heavy feed for a drill chuck/round shanked bit which is probably reduced down to fit in a 1/2" chuck, 65 sfm is ball park, but probably a bit fast for a drill press set-up. Hole saw will work fine, if done right, and leave a nicer finish on the wall. If you want a really nice hole, drill it 63/64, then ream it to 1", with parts stacked as DWF says. Many ways to do it, but low rpm's and a decent feed are the key in every case, doing it on a drill press anyway..

  10. #10
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    I understand your press drill might not take it but why not just drill 31/32" thru the plate and finish the hole using a 1" reamer with plenty of cutting fluid ?

    Heck, as you're at it, drill 3/8" as a pre-hole then just drill 1" straight with a properly sharpened drillbit. I'm assuming this would do a better job than a 1" hole saw.

    This is taking in consideration that you have the thing properly held in place of course.

    Good luck !

  11. #11
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    I flood cool use commercial water based cutting coolant (from Enco) a submersible garden fountain pump and a Homer bucket from home depot. I set the bucket under the table with about 4" of coolant in the bottom and the pump. PVC line from the pump up to the table and I direct the line, attached to an old dial indicator mag base, so that it pours (not sprays) onto the hole saw. Coolant drains off the table back into the bucket. Talking to some of the other home shop machinists, the pump will eventually die from ingesting metal particles, but for $12 I'll buy another. Mines been going for a year now using it once or twice a week. Makes for very easy miters through stainless tubing. I did this after I killed a couple of hole saws without cooling.

  12. #12
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    Quote Originally Posted by TgMN View Post
    Talking to some of the other home shop machinists, the pump will eventually die from ingesting metal particles, but for $12 I'll buy another.
    As long as it's not aluminium you're drilling, why not use a magnet in (or under) the bucket?
    I see hills.

    I want to climb them.

  13. #13
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    Thanks for all of the responses. I hadn't thought of a drill bit, as I thought the hole saw was much more efficient - removing less material. My drill press is pretty small, so I would need a bit that steps down to 1/2".

    I don't know if the stacking will work but I may try that too.

    Thanks again.

  14. #14
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    Quote Originally Posted by JaquesN View Post
    Thanks for all of the responses. I hadn't thought of a drill bit, as I thought the hole saw was much more efficient - removing less material. My drill press is pretty small, so I would need a bit that steps down to 1/2".

    I don't know if the stacking will work but I may try that too.

    Thanks again.
    The 1" drill will leave an ugly hole, especially on a small drill press. If you try it, drill .015-.020 undersize and follow it with a 1" reamer at about 200ish rpms and a nice decently heavy feed rate, and oil.

  15. #15
    DWF
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    You're not going to ream a 1" hole and get good results with brazing in a 1" tube. No filler clearance. Just a drilled hole is fine for what you're doing and the drill will automatically cut slightly oversize. If you have a problem with rigidity, drill a pilot hole just over the size of the flat on the 1" drill, like a #7 or 1/4" drill bit. Don't try walking up to the hole size with bigger & bigger drill bits. That's what core drills are for and they tend to be expensive.

    A sharp 1" drill bit will give you a good hole in 3/16 or 1/4" material on a drill press, even a cheesy one. Stacking the parts and drilling several at a time will give you better results. If you stack the parts, top clamp them with a step blocks & bridge clamps or drill press clamps. Do not try to drill multiple parts by holding them in a vise; the drill will simply lift them out and probably damage the part or the drill or you.

    For the drill bit, what you're looking for is a called a Silver & Deming pattern drill bit for use in a 1/2" drill chuck. Better ones will have delta flats on the shank to keep it from spinning in the chuck. See example here.

    hole drilling coolant question-61cj-jna51l._sl1500_.jpg
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  16. #16
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    How slow does your drill press go? That's where your problem is going to lie.

    I've made things like these in the past (not the ones pictured, I found that image on the internet) for my buddies jeep, with 1.5" holes, 32 holes. I used a single hole saw (though it was getting pretty tired in the end). In order to be successful with a hole saw you need it to go SLOW. I cut the holes in the 1/4" angle iron at 80 RPM, .0015" feed per revolution.



    Even with a 1" Drill bit yours going to be looking at 150-300 RPM in mild steel, even slower for chromoly.

    Trying to ram a 1" bit or hole saw though steel at 600 RPM just isn't going to work well.

  17. #17
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    Another point;

    If your machine does not have the torque to be making big chips while almost being bogged to a dead stop, then it is not really sufficient for this type of work. High RPM will not work, as you know. Think of the teeth of a hole saw or the edge of the drill bit the same as a single point cutter mounted in the tool post of a lathe. Same basic principle of making chips. It is a machining process, not an abrading one.

    We've all done cuts on marginal machines. If you can't slow it down enough by gearing, you do it by loading it heavily and bogging it to the proper speed. Hard on the machine, perhaps, but it will keep your cutter alive.

    Hole saws are a bit of a crude item, but they do work well for some things. Multiple holes in heavier flat stock is not really one of them. Neither are drill bits all that great for cutting thin stuff.
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
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  18. #18
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    Quote Originally Posted by Stevob View Post
    As long as it's not aluminium you're drilling, why not use a magnet in (or under) the bucket?
    I might give that a try. Won't help with the stainless but might improve the pump life with 4130.

  19. #19
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    Speed and feed makes all of the fifference in the world. I've machined some pretty tough materials over the years, with nothing but HSS, and gotten results that amazed the doubters, all because of knowledgable speed and feed choice.

  20. #20
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    I'm assuming you are wanting to make these yourself. If not, you might ask someone else to machine them. I could machine these via circular interpolation fairly quickly.

    Here are some things you may already have thought of or may already know.

    1) Not all holesaws are the same. A fine pitch Starrett or Lenox holesaw is a much better holesaw than something like a Home Depot special (Rigid).

    2) If your machine shows a deficiency in rigidity, consider making a box jig with an integrated drill guide of some kind. You could use a drill guide around the holesaw arbor, or if using a drill, around the drill proper.

    3) If you are drilling, pre-drill to the size of the drill web. A drilled hole, if done properly, leaves a good finish, and if the bit is sharpened properly, comes out damn near on-size.

    4) Consider making a trepanning tool that is well balanced if your machine does not have the oomph to push a drill. It might take a little bit to work out the proper cutting tool geometry, and you'd want to use a very small cutter (larger cutter takes more torque to push).

  21. #21
    Nemophilist
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    ^^Who Diss Guy?^^

    Good to have you hear, Mr. Whipsmart.

    Edit: Actually, that is a good if unintentional pun. Hear? Here? Both good for this board!
    Last edited by TrailMaker; 04-26-2013 at 04:32 AM.
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
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  22. #22
    The cat's name is jake
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    Hi John,

    I know, right? I've been on here for 10 years, but not even 100 posts. How do you have so many!?

    -Peter

  23. #23
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    Quote Originally Posted by BungedUP View Post
    Hi John,

    I know, right? I've been on here for 10 years, but not even 100 posts. How do you have so many!?

    -Peter
    Seriously, don't ask.

    John's a really good guy.

    Peter, what's your trade, you're not short of knowledge.

    Eric
    If I don't make an attempt, how will I know if it will work?

  24. #24
    The cat's name is jake
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    Hi Eric,

    By day I work as a fabricator for a tandem company in Eugene. I used to work for another Eugene bicycle company as a lot of different things. By night I'm a fabricator/machinist building a variety of things for other people/businesses. Before all that, I was a biologist, community college teacher, and researcher at a nearby university.


    I don't get time very often to post here, but once-in-awhile I just refuse to go work after work, and sit on the couch. It feels good!

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