Unibit Stepbit conspiracy theory - Page 3
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  1. #41
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    Hi MattiJ,

    Could you please provide a link to the manufacturer of those cutters.

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    Quote Originally Posted by Kiwi2wheels View Post
    Hi MattiJ,

    Could you please provide a link to the manufacturer of those cutters.
    Krino is the only "reputable" manufacturer I'm aware:
    Tools for cutting metal - Krino spa.

    I have ordered mine from hong kong/ebay.
    Even the asian import ones have been pretty good, difference to normal thick material hole saw is nothing short of amazing.
    Because the center drill "hangs out" only a 1/4" to 1/2" it actually does good job of keeping the drill centered and not chewing around like blind beaver.

    Here is one link to chinese ones from US based seller:
    5PCs 16-3mm HSS Drill Bit Hole Saw Set Ti-Coated Stainless Steel Metal Alloy | eBay
    or from Amazon:
    Mohoo 5PCS 16-3MM HSS Drill Bit Hole Saw Set Stainless High Speed Steel Metal Alloy - - Amazon.com

  3. #43
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    Quote Originally Posted by MattiJ View Post
    Krino is the only "reputable" manufacturer I'm aware:
    Tools for cutting metal - Krino spa.

    keeping the drill centered and not chewing around like blind beaver.
    Many thanks MattiJ.

    I've use the Hougen Rotabroach cutters in the smaller sizes but they are not easy to find in the larger diameters in Europe.

  4. #44
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    Quote Originally Posted by asawelding View Post
    So I'm pretty sure now that in some dimly lit conference room, thick with cigar smoke, there are a group of Billionaire tool manufacturers laughing at the ridiculous price tag they throw on multi-size sheet metal step drills. I just paid $60 bucks for a 3/16" - 1" bit..... And it appears they have all agreed never to manufacture them in carbide, because if the bit would stay sharp for a little while, then they wouldn't be able to sell you a new HSS one for $60 when your buddy roasts your bit trying to drill a dry hole through 3/8" 304 Stainless... End rantAttachment 138534
    .
    i never had problems with unibits maybe cause i do not run them too fast

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    I use Blairs, you can buy direct or even from amazon. They hold up very well and are still made in the States.

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    Perhaps a well to hold some vaseline/wax/blistex could assist as coolants.

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    typical small drill press has low speed of 500 rpm for normal 1/2" hss drill and obviously you would be going too fast with a 1" dia unibit

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    I work on a state highway sign crew and we use the smallest size ones (1/8-1/2") to drill everything from single signs to gang stacked signs, extruded Alu zee bar, even sch.40 & 80 pipe and W-beam flanges using a cordless impact driver and whatever cutting paste we have on the truck for ferrous and WD-40 for Alu.
    We predrill if we think it warrants it and go through 1-3 bits a year per truck. Irwin brand cause they have the 1/4" drive with the ball detent like the drivers.
    I didn't think that they would last as long as they do but it works. Maybe because the impacts effectively slow down the RPMs as they gain diameter? maybe someone can explain it to me, or tell me how I'm doing it all wrong and I'm going to get my man card revoked for abusing a step drill.

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  10. #49
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    Quote Originally Posted by DMF_TomB View Post
    typical small drill press has low speed of 500 rpm for normal 1/2" hss drill and obviously you would be going too fast with a 1" dia unibit

    That's 130 FPM, which is not too terrible for HSS, unless drilling stainless.

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    Quote Originally Posted by rklopp View Post
    That's 130 FPM, which is not too terrible for HSS, unless drilling stainless.
    typical larger size cutter hss should be going 10 to 75 sfpm. vibration can destroy a tool far before heat from high rpm. cant tell you how often somebody wants to run just a little faster and gets 200 to 1000% more sudden tool failures. longer setups and parts that vibrate require going slower cause of vibration. got nothing to do with tool getting too hot limits
    .
    all it requires is trying slower settings a few thousand times and record if its helping make more holes with reasonable tool life. cant tell you how often see people making the same mistakes over and over and over again. never learning.
    .
    typical cnc machinist looks for about 60 minute tool life if nothing else cause it is annoying changing tools every 20 minutes or less

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    I wonder how a sintered (pressed) carbide version would fare. With no real machining required, there might be some cost/price logic to it.

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    Since the Op has posted their "Conspiracy Theory", HF has deluged the
    market with a 3 pack of Chinese made copies, for $8.

    2 flute instead of the original single flute, Gold paint coated too.

    So the whole subject is null & void.

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    Quote Originally Posted by CalG View Post
    I wonder how a sintered (pressed) carbide version would fare. With no real machining required, there might be some cost/price logic to it.
    .
    .
    carbide is brittle.
    .
    i always laugh when somebody wants to use carbide hole saw on steel with a hand drill. usually doesnt even last one hole.
    .
    some of us actually can make a unibit last over a 100 holes without saying anything about a conspiracy

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  19. #54
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    Quote Originally Posted by Nicodaemus View Post
    I work on a state highway sign crew and we use the smallest size ones (1/8-1/2") to drill everything from single signs to gang stacked signs, extruded Alu zee bar, even sch.40 & 80 pipe and W-beam flanges using a cordless impact driver and whatever cutting paste we have on the truck for ferrous and WD-40 for Alu.
    We predrill if we think it warrants it and go through 1-3 bits a year per truck. Irwin brand cause they have the 1/4" drive with the ball detent like the drivers.
    I didn't think that they would last as long as they do but it works. Maybe because the impacts effectively slow down the RPMs as they gain diameter? maybe someone can explain it to me, or tell me how I'm doing it all wrong and I'm going to get my man card revoked for abusing a step drill.
    I've used step bits many times with a cordless drill and they last quite a while if the RPM is kept low and a good lube is used.

    I've even used them years ago in a tiny drill press (with good lube) to drill the steel mounting bars for a Rockwell/Delta table saw fence to a different configuration to match a DIY extension table. I made a particle board jig to locate the hole spacing per the factory ones and retracted the bit frequently for cooling/chip removal, and lube. The bits were unharmed after this rather severe use.

    Where step bits excel is in enlarging existing holes.

  20. #55
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    its like the worker who thinks everybody at work out to get him or there is a conspiracy. type you see on the news sometimes.
    .
    1/2 a bubble off we used to say

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    Quote Originally Posted by digger doug View Post
    Since the Op has posted their "Conspiracy Theory", HF has deluged the
    market with a 3 pack of Chinese made copies, for $8.

    2 flute instead of the original single flute, Gold paint coated too.

    So the whole subject is null & void.
    The HF step drills are absolute crap!

    They do not even have proper cutting geometry and leave heavy burrs on the back side of the hole.

    For really fussy stuff like an electronics panel I use my real Unibits and for rougher work the Irwins. FWIW I occasionally hand hone the face of the cutting edges which greatly improves bit life.

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    Quote Originally Posted by Scottl View Post
    The HF step drills are absolute crap!

    They do not even have proper cutting geometry and leave heavy burrs on the back side of the hole.

    For really fussy stuff like an electronics panel I use my real Unibits and for rougher work the Irwins. FWIW I occasionally hand hone the face of the cutting edges which greatly improves bit life.
    Who cares !

    The OP wouldn't know the difference, and burns them up in record time
    no matter who made them.

    Plus, it's all a conspiracy, time for the OP to line his hardhat with tinfoil.

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    Now I'm sure I saw a unibit being used on the second floor of the Dallas Schoolbook Depository that fateful day in Nov. '63.

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  26. #59
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    Quote Originally Posted by DMF_TomB View Post
    .
    .
    carbide is brittle.
    .
    i always laugh when somebody wants to use carbide hole saw on steel with a hand drill. usually doesnt even last one hole.
    .
    some of us actually can make a unibit last over a 100 holes without saying anything about a conspiracy
    You must be right.

    That is why they make the "teeth" of stump grinders and pavement mills from carbide. The carbide chips make an abrasive mixture that speeds the cutting action (No! NOT really)

    Perhaps there would be a sintered grade that would best the material that is presently used.\


    My angle was the "Minimum machining/grinding" that might be offered through sintering. Perhaps the step frill geometry is unsuitable , but it is not because "carbide is too brittle". Some carbide grades are too brittle, but there are many.

  27. #60
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    Quote Originally Posted by Scottl View Post

    Where step bits excel is in enlarging existing holes.
    I always thought that's how they're supposed to be used.


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