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#1
Old 11-27-2011, 08:09 AM
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Why can't rotary tools (Dremel) be used as screwdrivers?

Is it because of torque? Isn't that just a matter of adding gears?

Additional question 1: can cordless screwdrivers be used as drills?

Additional question 2: how interchangeable are the accessories? Specifically, can I use Dremel bits on a Black & Decker tool? Thanks.
#2
Old 11-27-2011, 08:43 AM
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Dremels spin FAR to fast to be used as a screwdriver, and I don't think they have enough torque either. The slowest they go is several thousand RPM. Screwdrivers run between essentially zero and a few hundred RPM. If you put a screwdriver bit in a dremel and tried to screw something in, I'd guess that the dremel would either stall or rapidly nibble the bit and head to nothing.

Cordless screwdrivers work just fine as drills. You wont be drilling large holes through hard materials with a small screwdriver, but otherwise any decent screwdriver can drill holes just fine.

Bits are pretty much completely interchangeable. Other accessories aren't: some Dremel molded plastic cutting guide probably won't fit on any other brand of cutting tool.

Last edited by lazybratsche; 11-27-2011 at 08:45 AM.
#3
Old 11-27-2011, 09:11 AM
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consumer cordless screwdrivers (pistol grip drill like in shape) likely have a torque setting that lets them work better as a drill.

mini rotary tools often use a chuck for a 1/8" shaft. thing you place in it should match the tool for its speed and power. some accessories, besides things that go in the chuck, may be tool specific.
#4
Old 11-27-2011, 09:24 AM
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Stall speed/torque. The Dremel will keep trying beyond what you want for a screwdriver. That's why drill-screwdrivers have a torque ring (the best of them, and part of the reason). Of course the fitting differences keep it from being practical.
#5
Old 11-27-2011, 09:58 AM
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No torque or watts

Those little motors have only 1.15A motors so you can figure the watts at no more than 140. They also have no torque at the low speed needed for driving screws. Plus the connection between the motor and the driver inside is a plastic tube that won't handle any torque before breaking. (I have used rubber hose as a replacement.)

But yes in a way they can be used for drivers. I have seen precision drivers that use the same or smaller motor driving through multiple reduction gearing to provide the exact torque needed for sensitive assemblies. They can equal the final torque of an 18VDC drill driver. Both Sears, B&D and others used to make drivers with tremendous torque with these motors using only two "C" size Ni-Cads. They would drive hundreds of screws on a charge. I still have one left hooked to a 12VDC battery that does a great job in tight spaces.
#6
Old 11-27-2011, 12:23 PM
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Quote:
Originally Posted by Al Bundy View Post
Those little motors have only 1.15A motors ....

I have seen precision drivers that use the same or smaller motor driving through multiple reduction gearing to provide the exact torque needed for sensitive assemblies. They can equal the final torque of an 18VDC drill driver.
In other words, it's not about the power (watts or amps) of the motor, it's about the gearing and/or motor design. If a motor+gear is set up for high speed, it won't produce much torque at low speed. If a motor+gear is set up for low speed and high torque, it won't spin very fast. That's why you can't use one device for both purposes, unless you can change the gear ratio.
#7
Old 11-27-2011, 12:26 PM
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Quote:
Originally Posted by scr4 View Post
In other words, it's not about the power (watts or amps) of the motor, it's about the gearing and/or motor design. If a motor+gear is set up for high speed, it won't produce much torque at low speed. If a motor+gear is set up for low speed and high torque, it won't spin very fast. That's why you can't use one device for both purposes, unless you can change the gear ratio.
like cordless drills. They have a high-speed motor and a planetary gearset to provide the gear reduction needed to have sufficient torque. better ones also let you select the gear ratio for either higher speed (drilling) or higher torque (driving fasteners.)

IMO if you only have one tool, it should be a cordless drill of reasonable quality.
#8
Old 11-27-2011, 12:31 PM
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While I'm sure some do, most electric screwdrivers/drills I've seen do not have different settings: You just stick the appropriate bit in and go.
#9
Old 11-27-2011, 12:33 PM
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Originally Posted by jz78817 View Post
IMO if you only have one tool, it should be a cordless drill of reasonable quality.
and maybe the biggest issue is the battery. shop carefully for ones with good batteries, just a name brand might not be an indication of that.
#10
Old 11-27-2011, 12:36 PM
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Quote:
Originally Posted by Chronos View Post
While I'm sure some do, most electric screwdrivers/drills I've seen do not have different settings: You just stick the appropriate bit in and go.
Really I the ones I've ever used or owned have had a setting ring 1-10 or 1-25. Although I have to admit I have never used any setting but 1 or 10/25, either full torque for driving, or full speed for drilling.
#11
Old 11-27-2011, 12:39 PM
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Quote:
Originally Posted by wolfman View Post
Really I the ones I've ever used or owned have had a setting ring 1-10 or 1-25. Although I have to admit I have never used any setting but 1 or 10/25, either full torque for driving, or full speed for drilling.
those are clutch settings, which let you set at about what torque the chuck will start to slip so you don't over-torque whatever it is you're driving. The setting I'm talking about is gear selection for low- or high-speed drive.
#12
Old 11-27-2011, 12:42 PM
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That adjustable ring is just the clutch that sets a torque limit, it doesn't change the speed. "1" is minimum torque, "10" is maximum. For drilling you don't want to limit the torque. For driving, you want enough torque to drive the screw, but not so much that you tear apart the head. Most drills have variable speed controlled by the trigger pressure. In addition, some cordless drills also have a gearbox that can switch between higher and lower speeds.
#13
Old 11-27-2011, 01:12 PM
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Quote:
Originally Posted by Chronos View Post
While I'm sure some do, most electric screwdrivers/drills I've seen do not have different settings: You just stick the appropriate bit in and go.
Any decent screw gun needs clutch-type settings to prevent stripping the screws.

The speed can be adjusted, if needed, by depressing the trigger more/less.
#14
Old 11-27-2011, 04:15 PM
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It might just be that the ones I'm thinking of were purpose-built as screwdrivers, and just occasionally used as subpar drills. We did a lot more screwdriving on that job than drilling.
#15
Old 11-27-2011, 10:56 PM
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Ah why don't they add gears so rotary tools can be used as screwdrivers, then? Does it degrade the other functions? Or maybe rotary tools and screwdrivers are used in different places?

I wanted to buy a Bosch Li-ion screwdriver (IXO 3), then I realized it doesn't have torque settings! How odd for a high-end tool. The GSR 10,8-2-Li looks pretty good though.
#16
Old 11-27-2011, 11:23 PM
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if the tool is specialized it can be smaller for ease of use both for size and weight. when a tool is used for long periods of time, as professional or serious craft tools, those factors are important.

a general use consumer tool, used for shorter periods of time, could be bulkier, be more featured so that a single tool only need be purchased.
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