Square drive bits for Centrotec
- Thread starter stvrowe
- Start date
I'm "across the pond" here in metricland and I use square drives only because I use Kreg jigs and I can't find the proper screw profile here in Europe. I would be just as happy w/ torx if I could find the proper head shape and thread/shank ratio.
This thing has turned into an ugly "Chevy/Ford" argument. I see it as companies forcing us into buying "their product" based on marketing strategy.
Next week, Dack and Blecker will release the 4th dimensional anti-gravity drive and the screw will become obsolete.
???
This thing has turned into an ugly "Chevy/Ford" argument. I see it as companies forcing us into buying "their product" based on marketing strategy.
Next week, Dack and Blecker will release the 4th dimensional anti-gravity drive and the screw will become obsolete.
???
Jim Becker
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I did cam out a square drive screw the other day while doing some shop rearrangement. Then I realized I had a Phillips bit in the TDK-12. Silly me... :
WarnerConstCo.
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GRK's are even distributed out of Canada.
Dave Ronyak
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I, too, don't understand why Festool doesn't offer square drive (Robertson) bits for Centrotec chucks and holders, but it isn't that difficult to modify bits you can obtain inexpensively from others, as discussed and demonstrated earlier in this thread. It is obviously due to my lack of proper [alignment] technique, but I find that I have a lot more problems driving square drive screws than driving Phillips head screws (genuine Phillips brand) with a genuine Phillips bit. When driving pocket hole screws made by Kreg with a Kreg bit, the bit frequently won't engage the screw or disengages from the screw due to only slight misalignment. My experience with McFeeleys square drive decking screws versus Phillips brand decking screws is similar. The key is proper fitment of the driver bit to the recess in the head of the screw; many of the foreign (Chinese?) manufacturers today don't pay enough attention to the dimensions and tolerances that are needed for reliable connection of bits and screws.
Dave R.
Dave R.
markchamness
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leakyroof
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I have read that much like Torx screws and their imitators, Robertson screws are slightly different than just plain square drive screws. The taper on the bit has to be a certain angle, and cheap copies don't bother with that for either the driver bit or screw head recess from what I'm told.Dave Ronyak said:
GhostFist
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I just wanted to post how much I hate the BHS65 or what ever the hell that over priced piece of garbage is called and how happy i am that ATLAS manufactures excellent quality centrotec Robbies. Though I'm also somewhat upset at ATLAS for selling me to BHS65's because they both crapped out within months.
hockey_magnet
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leakyroof said:
Actually I believe the true Canadian Roberston bit is ALMOST straight edged and are actually sometimes 2 pieces whereas "square drive" bits have more of a taper and are always one piece. The Robertsons do not hold the screws on the bit as well but tend to cam out less than the square drives. Lee Valley mentions this:
Lee Valley Robertson bits
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I suspect that all modern square-recess heads have tapered internals.
To make a truly parallel-sided, square shouldered impression in steel would almost require drilling and broaching the hole. (1) There are other modern processes but they would be prohibitively expensive for screws.
Considering the strength required, I suspect that the heads of internal square-drive screws are forged or cold formed with a tapered punch of some sort. Inserting anything in a hole without cutting, almost certainly requires a taper on the impregnator.
In the case of Robertsons, I would assume it's a serendipitous advantage. Apparently, when tolerances of the cavity and the driver are tight enough, the tapered surface(s), and there are four, tend to help hold the fastener to the driver.
That same advantage exists with other fastener designs that are more torque intensive. The key is the fastener-to-driver tolerances.
Tom
(1) I've worked where we designed holes in steels and, mostly, BeCu and then broached them for 1/4" and 3/8" ("standard") square drives. We could afford to do it because money was of little concern and our manufacturing volume was low.
To make a truly parallel-sided, square shouldered impression in steel would almost require drilling and broaching the hole. (1) There are other modern processes but they would be prohibitively expensive for screws.
Considering the strength required, I suspect that the heads of internal square-drive screws are forged or cold formed with a tapered punch of some sort. Inserting anything in a hole without cutting, almost certainly requires a taper on the impregnator.
In the case of Robertsons, I would assume it's a serendipitous advantage. Apparently, when tolerances of the cavity and the driver are tight enough, the tapered surface(s), and there are four, tend to help hold the fastener to the driver.
That same advantage exists with other fastener designs that are more torque intensive. The key is the fastener-to-driver tolerances.
Tom
(1) I've worked where we designed holes in steels and, mostly, BeCu and then broached them for 1/4" and 3/8" ("standard") square drives. We could afford to do it because money was of little concern and our manufacturing volume was low.
