Maker Pro
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cordless motor project

Jon_

Nov 27, 2022
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Nov 27, 2022
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Hello all!

I am new to this community and I appreciate the advice that you may have for me! I have little experience with electronics but have plenty of experience with tinkering and building things.

I have a friend who has a foredom motor that is used with a massager. (foredom massager)

They need to use it where there is no power. Currently they have a battery hookup but the unit is too heavy plus the heavy battery that has a AC outlet for the motor.

I figured i could make help her out and make her a cordless unit that uses a dewalt or milwaukee battery etc setup to make it easier for her travel.

My idea so far is to do the following setup but need advice.

Battery (LION) > Adapter with fuse> Voltage disconnect (to not over drain battery) > DC speed controller (she adjusts spped as needed) > a quiet! motor

What motor can I get that is super quiet?
This is where i really need help, selecting a motor. This setup that she uses is for large animals in rehab situations hence the cordless part. We tested a cordless dental tool for horses that used makita batteries and it made such a loud noise that she said it would spook the animals and she would need hers to be quiet. Large animals are sensitive to frequency and chatter from gears. We can spend some money like 100-200 range for the motor vs the cheap amazon stuff but need help picking out a super quiet motor that will do the job.

we'll have to have an adapter made to connect to the flex cable unless there is a motor with a 5/16 diameter shaft with a flat edge. (that is how the flex shaft connects currently) - here is a diagram of a foredom motor breakdown if needed - parts diagram

Is it better to have a 12V or 20V battery?
I have dewalt batteries as I do construction work so I have them to test with but I also have milwaukee 12V units. They sell a 12v power supply from milwaukee - power source - that may make it easier? but the 12v batteries might not last long?

How is the quality of amazon parts like voltage disconnect and dc speed controller?

If i pickout some compionents from amazon i feel like they will burn out pretty quickly. Would rather spend 20 vs 5 if it means it will last.


Other info I have figured out.

Current motor from foredom is 400-4400 RPM, hard to decipher which model they use for the massager but the other units are 1/6 HP and 1/3HP.
Online calculator shows 0.53Nm if i did a 1/3Hp at 4400
and 24Nm at 100 rpm.

For her massager setup the torque needed would seem to be low for her needs however the motor they make is for carving tools etc that require alot of torque. This is a soft pad that runs along muscles. There are times that it is pushed lightly into the muscle but from what she showed me it is very light touch 99% of the time.

I appreciate any help and advice you guys may be able to give me on this project.

Thanks!

Jon
 

kellys_eye

Jun 25, 2010
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Worst case, a 1/3hp motor is around 250watts. At 12V this would mean a motor drawing 20 amps from a battery so your typical 4-5Ahr Dewalt would last 10 minutes - if you're lucky (and it doesn't overload the battery).

Motors are relatively easily 'silenced' by mounting them in an enclosure with suitable flexible supports for the motor (isolating it from the case it's in) and extra sound insulation inside the case as necessary.

You'd get better performance using a car battery or manufacturing a larger Lithium battery using series/parallel cells for a greater capacity - there may (probably are) larger 12V Lithiums on the market but don't expect 'cheap' plus add in the cost of the charger.

It may be more practical (simpler) to use a battery inverter (12V to 120/220, whatever) - the better versions have 80%+ efficiency and keep the original mechanism. Figure on a 500W inverter and budget around $150. Fabricating an alternative motor/mount etc won't be that easy.


Power the inverter from your car battery (suitable outlet and fuse from battery) parked up near the animal - I'm sure they won't mind a stationary car near them?
 

Jon_

Nov 27, 2022
3
Joined
Nov 27, 2022
Messages
3
thanks for the reply!

I am going to guess that the motor is not pulling 1/3 hp. There are many types of dental equipment that use same setup with flex cables for horse dentistry, just too noisy since its most likely made with cheap motors and gears. they state that the makita battery will give enough at least 30 mins a battery. here is a product for reference: dentist product

here is another that uses something that looks like makita brand... tool

as for inverter etc, she already uses that, with the current foredom motor and battery pack it is a bit heavy over time for her. Ill figure something out that may make it easier.

I appreciate your advice, thank you.
 

Martaine2005

May 12, 2015
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May 12, 2015
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Both units you linked to are Makita.
By definition, these are construction tools with different gearbox or Chuck/shaft housings.
I think you’ll need to buy LOTS of different types of motors to try. This will most definitely be a trial and error scenario.
Most, if not all motors are fairly quiet at low RPMs and quite noisy at higher RPMs.
In most cases with animals, it’s about introducing noise or umbrellas! Slowly to familiarise and get accustomed to.
I do a lot of oak work around horses and they hate the noisy tools to begin with. By the second week, they take no notice unless it rains and I put up an umbrella!. Then they freak out. So they need to be around people with umbrellas more often.

Martin
 

kellys_eye

Jun 25, 2010
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Modifying housings to take different motors will wear you down quicker than the tool does..... no motor is going to be particularly quiet on its own. As I mention, it's all down to physical housing and vibration mounting to keep any motor quiet.

As for not pulling 1/3hp.... no, most motors won't - until it's necessary i.e. when the load builds. Then, if the motor isn't sufficiently rated it will burn out if it doesn't have the required 'hp' to keep turning. Far better to over-rate than under-rate.

If the equipment is heavy then maybe a simple pull-along cart with everything fitted would be more appropriate. Dewalt (and others) make such tool carts with differing sized cases that stack. One for the battery, one for the inverter, one for the tool and an extension reel/cord for 'remote' use.
 
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