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  1. #1
    smootz's Avatar
    smootz is offline Stainless
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    Part of a quote I am working on requires (600) 1" diameter drilled holes in 3/4" A36 plate. I am thinking Hougen drill with a Rotobroach.

    I have used Hougen drills in other shops but never on this many holes. I was thinking about buying one of the 904 series.

    Can anyone give me advice on bit life? (How many holes should I expect from each bit?) Also how long you think it may take to drill this many holes?

    Thanks for any advice, SCOTT (fabricator - wanabee machinist)

  2. #2
    Konrad's Avatar
    Konrad is offline Cast Iron
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    Have never used them but we sharpen them....Iwould think 3 bits should do it if everything is set up right.
    Can you not drill them in a drill press?
    Konrad

  3. #3
    smootz's Avatar
    smootz is offline Stainless
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    There are 4 holes each in (150) plates that weigh about 28#/ea.
    Drill press is an option but I would need to pick up a heavier one. Mine is pretty light for that many 1" holes. Plus the extra time to drill pilot holes. I use the Bridgeport for small holes but figure this would be pretty hard on it.

    SCOTT (fabricator - wanabee machinist)

  4. #4
    jkilroy is offline Diamond
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    600 holes? Whatever you do, make sure you get a drill with power feed if they make them.

  5. #5
    Ries's Avatar
    Ries is online now Diamond
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    A couple of years ago, we had a job where we had to drill several hundred holes with the mag drill, using rotobroach bits.
    Mostly 1/2" holes in 5/16" 316 stainless. (and no, we didnt get the magnet to stick to the stainless. the stainless was bigger than the throat of any of my drills or mill, so we made a big bar of 1/2" x 4" flat bar that clamped over the stainless, for the mag to grip to)
    So the holes were smaller, but the material was harder. We were averaging around a hundred holes between resharpenings.

    So I think that Konrads guess of 200 holes is about right, in mild steel. Use coolant/lube, and you can send one to be sharpened while the other one or two is drilling. If you need to do em all in two days, then yeah, you need to buy 3 bits. But if you can stretch it out a bit, you can send bits in to be sharpened, and get away with two bits.

    600 holes doesnt seem worth buying a $5000 drill press to me- we drilled over 6000 holes in stainless on that job, mostly 1/4", using the quill on the bridgeport and a rotary table- it wasnt hard, the machine is doing all the work.

  6. #6
    smootz's Avatar
    smootz is offline Stainless
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    If I buy a larger drill press it will not be a $5000- one. Something surplus is more my style. The Hougen however can be picked up new for $800-$900-. Maybe a good excuse to get a useful shop tool?

    1/4" holes would not bother me on the B-P but I have been advised not to use the machine as a drillpress. So I am thinking 1" holes in 3/4" plate would be hard on it. Have I been poorly advised?

    SCOTT (fabricator - wanabee machinist)

  7. #7
    Scott R is offline Hot Rolled
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    Scott
    Did you look at HGR in Cleveland? You should be able to get a radial arm drill press for $1500 or so that would work for you. Welding shop can allways use a radial drill. And using your Bridgeport for drilling 600 1" holes would destroy it. Anything over about 5/8 I bore it on a BP unless it was thin stock and I could use a hole saw.

    Is a Hougen Drill just a mag drill or is it more like a Rotobroach?

    Scott

  8. #8
    Forrest Addy is offline Diamond
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    Don't forget to grind the mill scale off the plate where the holes go. It will triple the roto-broach life.

  9. #9
    Lumpsmith is offline Aluminum
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    Who told you not to use your Bport for a drillpress? What do you think it was made for? trust me that is one great drillpress and with rotabroach cutters 1" holes in steel will be easy,like others said use coolant,grind off the scale,and run it at a slower speed.Rotabroach cutters rule!!

  10. #10
    smootz's Avatar
    smootz is offline Stainless
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    Thanks for the advice guys. I think I will bid this at about 5 min per hole and figure 4 cutters.

    I hope I am not shooting myself in the foot.

    I will keep my eyes open for a good deal on a radial drill but until then I think an $800- mag base Hougen would be a handy item for future jobs as well.

    Scott R,
    I see HGR mentioned fairly often. You know where I am. Would that be about 5 or 6 hours from me? Tell me about them and give me contact info.

    Thanks, SCOTT (fabricator - wanabee machinist)

  11. #11
    Ries's Avatar
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    Buy the mag drill- you will love having it around.
    There are lots of cases where its MUCH easier to take the drill to the work.
    We often build big steel doors- 4 or 5 feet wide, 9 feet tall, framed with 2" square tube, 1/4" wall- so by the time they are done, they weigh 300-500lbs. Then we want to prehang em in the shop- and inevitably, steel moves when you weld it, so we drill the holes for mounting the hinges with a mag drill- handy, quick, and a whole lot easier than manhandling a 500lb 9 ft long gate.
    Or things that are just too big for the throat of the available drills- sure, a 5 ft. radial drill would be nice- but where I live, they dont go for scrap prices.
    We take the mag drill on job sites all the time too, and there is nothing better for that- we were on a site last month, drilling 9/16" holes in channel 35 feet up, wearing fall protection- nothing but a mag drill could have done that job, but with the rotobroach bits, it was relatively easy.

    I cant imagine why you couldnt drill in a bridgeport- there is no axial loading on the spindle, and no wear on the dovetails- it seems like it would be a lot LESS bad for the machine than actual milling?
    Or am I wrong, and is there some mysterious reason why you shouldnt drill on a bridgeport?

  12. #12
    Pete28 is offline Plastic
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    I have used Hougen mag base drills for years with excellent results. Even on big aluminum plates by clamping a steel plate in between. I think that using them for 600 holes would use up a lot of time positioning the base over each hole location. Locating isn't hard, just a little time consuming. You may want to consider getting the adapter and using the Hougen broach cutter in a standard drill press. I do this in the shop more than using the mag base. Mag base best in the field. Because the broach only cuts a holesaw-like path it is much less demanding on the drill press than a twist drill that scoops out all the material. Forget how many bits it will use up. That's part of the job. With lots of lube oil and regular chip removal you should do just fine. Like Konrad says, three should do it. So get a couple extra. If the operator hiccups at the wrong time, the broach can snap. Good luck.

  13. #13
    smootz's Avatar
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    I have only owned the B'port for a few months and I really don't know it's capabilities. It is a primo condition machine and I am very cautious with it. More than one of my mentors have suggested that it is not designed for heavy drilling. I honestly don't know but I am a person who rarely pushes a machine to it's limits.

    For this job I am thinking the mag drill will eliminate some material handling, clamping, repositioning.

    SCOTT (fabricator - wanabee machinist)

  14. #14
    metlmunchr is offline Diamond
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    In the interest of putting together a competetive price, you might want to see what it would cost to sub the drilling to someone with a VMC. 4 one inch holes in 3/4 plate would take 5 minutes or less floor to floor in a VMC, with the operator deburring the holes on a finished part in a drill press with a countersink while the next part is in the mill. Setup time amortized over 150 plates would add little to the individual cost. If they can be drilled in a drill press then they can be done in a VMC in a single shot with no spot drilling or lead drilling. Might come out cheaper than you can do it yourself. I'd run them all day long for $7/plate and have lotsa money at the end of the day

  15. #15
    smootz's Avatar
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    If you lived closer I would give you the job. All the big shops here are full of work. They are subing all the small jobs to little guys like me.

    I am not as machinist but I am doing more simple machine work lately than fab. Four quotes this morning.

    I am thankfull I have you guys for advice.

    SCOTT (fabricator - wanabee machinist)

  16. #16
    toolmakerjim is offline Titanium
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    muncher;
    where Scott lives there are quite a few machine shops but CNC's are pretty rare. there are a few in Huntington WVa but they are in job shops so that may affect his profit margin sustantially.
    now i think he should look into getting a used VMC which would let him be more efficent and allow a better range of performing work which will open up more work for him.
    most people dont realize that that area of Ky/Oh/WVa has LOTS of industry but the shops there are mostly old with equiptment from the early 20th century.
    if it were me i would just go ahead and drill the 1" holes on the Bridgeport using a Silver & Demming style drill. it wont affect the machine but none the less thats still a lot of holes on a BP.
    if the job looked like it would repeat make a drill jig using slip renewable bushings.

    but look into this Scott. call Ky Tech in Ashland or Lawrence Co. Vo-Tech at Getaway and see if they can put this job on their CNC's that may be the best solution..jim

  17. #17
    Wooderson is offline Aluminum
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    Scott,

    Here is the search page for HGR. Located in Euclid, OH 44117.

    Andy

  18. #18
    Scott R is offline Hot Rolled
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    Hey Scott
    Yeah, Your probably 5 hours from me. Maybe less in a car. If you call HGR talk to Brian Kruger I have delt with him for years and he is a pretty straight shooter. Tell him Scott from Allwoods sent ya. And I got a mag drill you can try as long as it makes it back up my way
    Scott

  19. #19
    secetal is offline Hot Rolled
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    Scott, Go with the Hougen, I have one and love it,I also use the cutters in my B-ports. Martin

  20. #20
    smootz's Avatar
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    I picked up a Hougen catalogue today. There are adapters to use the rotobroaches on a morse taper, an R8, and even a 1/2" straight shank.

    Now I am thinking about using the R8 equipped broach on the B-P. Would that be a lot to ask of the power down feed?

    I'm weighing the difference in clamping the part down and repositioning the table for each hole vs. moving a mag drill 600 times.

    Jim,
    You may not live here anymore but you still understand the area. What few CNC machines exist here are full of work. That's why us country boys get to use our antiques. Appalachia ----- you either love it or you hate it. A lot of Jeff Foxworthy's material originated here.

    BTW. What is a "Silver and Demming"?

    SCOTT (fabricator - wanabee machinist)

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