Erbauer impact driver too fast!

[JBR]

Model: ER16921PD

This works well enough with one exception: however careful I am in pulling the trigger as gradually as I can, the thing tends to speed up far too quickly.
Is there any way I can moderate the speed so that I can turn it slowly, especially when first driving in a screw?
I'm assuming that there is a variable resistor behind the trigger to which, I suppose, I could add another resistor (if I knew what value) in the circuit, and that's assuming I can undo the deeply recessed screws which hold it together!
Or perhaps there's an easier way?
It is out of warranty, so I'm happy to do this. Thanks for any advice.

 

[blup]

The basic ones are designed to go full pelt or are your saying its got worse. Makita do models with different speeds and slow starts.

Blup

 

[JBR]

Thanks for your very quick reply. I'm not sure of being designed to go full pelt, because is it possible to make it start slowly. I just have to try to pull the trigger very gradually, but even then it is very difficult to control the speed. No it hasn't got any worse. In fact, I should have asked for advice soon after I bought it, but decided to struggle on!

 

[HERTS P&D]

What make is it?

Andy

 

[JBR]

What make is it?

Andy

Erbauer

 

[HERTS P&D]

It looks like the Erbauer doesn't have any speed settings.

Andy

 

[Harry Bloomfield]

If it is variable speed depending on how much you squeeze the trigger, then if the trigger doesn't also directly control the motor current via some electronics, then you could add a resistor in series with the trigger speed control. Measure the resistance of the control, at the initial part of the 'squeeze', then try adding a resistor in series with it of equal value.

Problem - as voltage on the motor is reduced on such a basic control method, the torque is reduced to a much larger extent. Probably why the items starts off so quickly anyway, but worth trying. Better is a full voltage pulse system, with variable pulse width to determine the average current. Best, is a feedback system of applying enough voltage and current, so the speed nicely matches how hard the trigger is squeezed, irrespective of load, up to a limit.

 

[Deleted member 174758]

Impact drivers aren't like drill/drivers - the basic (i.e. "one speed") models like the Erbauer are designed to be all or nothing, e.g. to drive home large construction screws like those you use in timber framing hard, and nothing more. If you want an impact driver which will drive smaller screws and be much more controllable, the only option is to look at a multi-speed impact driver like my Makita DTD171, or the previous Makita I had for about 9 years, the BTD145. These feature 4 and 3 main speeds respectively as well as reduced torque on the slower settings, however they are top of the line tools with price tags to match.

To an extent it is possible to moderate the speed of a single-speed impact driver by "feathering" the switch (i.e using very light trigger pressure, continuously pressing and releasing the trigger switch - a bit like the detente braking you employ a car when driving in extremely wet or icy road conditions), but there is no way to guarantee a smooth increase of speed or fine control with a single speed impact driver. For that you are fsr better off going to a combi drill or drill/driver which has a more complex variable speed switch mechanism, or buy a much more expensive multi-speed impact driver

 

[Deleted member 174758]

If it is variable speed...

They aren't variable speed, though. Impact drivers are designed to impart the maximum amount of torque to a screw or fastener to drive it into materials. They do this by rotating a hammer at high speed into an anvil just behind the 1/4in hex bit chuck. The hammer is designed in such a way that it strikes the anvil but in doing so the spring which presses the hammer upwards into the oath of the anvil is compressed and the hammer drops out of the way, allowing the motor to accellerate the hammer up to speed again (the faces of the hammer is angled). By the time that the hammer has done one rotation the spring has pushed it back upwards into the path of the anvil, which it strikes again...and so on

A system designed to increase torque in this way works best when the motor is rotating at the highest possible speed. If your intention is to drive heavy coach screws or 6.0 x 100mm framing screws into framing timber (the actual purpose of an impact driver) then the system works well

It is only by going to a brushless motor that you can get sufficient torque to make it worthwhile incorporating any form of speed control. In reality to get true control over driving fixings with this class of tool you need to go to a torque converter type of transmission, such as that you find in an oil impact driver.

 

[JBR]

If it is variable speed depending on how much you squeeze the trigger, then if the trigger doesn't also directly control the motor current via some electronics, then you could add a resistor in series with the trigger speed control. Measure the resistance of the control, at the initial part of the 'squeeze', then try adding a resistor in series with it of equal value.

Problem - as voltage on the motor is reduced on such a basic control method, the torque is reduced to a much larger extent. Probably why the items starts off so quickly anyway, but worth trying. Better is a full voltage pulse system, with variable pulse width to determine the average current. Best, is a feedback system of applying enough voltage and current, so the speed nicely matches how hard the trigger is squeezed, irrespective of load, up to a limit.

Thanks. Very helpful, especially the emboldened details, though I accept that I would likely lose some torque. The more complex ideas, I'm afraid, are probably beyond me though!

 

[JBR]

Impact drivers aren't like drill/drivers - the basic (i.e. "one speed") models like the Erbauer are designed to be all or nothing, e.g. to drive home large construction screws like those you use in timber framing hard, and nothing more.

To an extent it is possible to moderate the speed of a single-speed impact driver by "feathering" the switch (i.e using very light trigger pressure, continuously pressing and releasing the trigger switch - a bit like the detente braking you employ a car when driving in extremely wet or icy road conditions), but there is no way to guarantee a smooth increase of speed or fine control with a single speed impact driver. For that you are fsr better off going to a combi drill or drill/driver which has a more complex variable speed switch mechanism, or buy a much more expensive multi-speed impact driver

Thank you. I did buy it originally for the sort of procedures you first mention, but I was hoping to use it more generally as well.
I have tried using the 'feathering' procedure you mention with some small success, and I do have a DeWalt combi drill as well which is much more controllable, but bigger and less convenient for restricted spaces.

 

[catlad]

Unless you are driving 75mm x 5mm and above screws a lot! then you don't need an impact driver as they are not as versatile as a normal combi drill.

 

[JBR]

Unless you are driving 75mm x 5mm and above screws a lot! then you don't need an impact driver as they are not as versatile as a normal combi drill.

Thanks. I realise that now of course.

 

[foxhole]

I have dewalt three speed , easy to control, been using today for plasterboard and sinks screws in same depth time after time.

 

[big-all]

yes a brilliant bit off kit electronic speed and electronic gear box equivilent so no actual gears to go wrong
https://duckduckgo.com/?t=ffsb&q=dewalt+887&atb=v227-1&ia=web