Electrical Advice Needed

[Valuesize]

I need a more reliable (cheap) motor for my coffee roaster. I've been using a variable speed drill I bought at Harbor Freight but it doesn't have enough torque to turn more 2 1/2 lbs. and I'd like to turn 4-5.

For cheap motors, some guys use bread makers or ice cream makers from Goodwill because they have plenty of torque and can be found for $5-$10. I need to be between 30 and 50 rpm's and would prefer to change speeds depending on the size and stage of roasting.

So I guess what I'm asking is what and where can I buy something to create a variable speed roasting motor without spending much $$$$.

Here is an example of what my roaster looks like equiped with a nice motor. I haven't bought a Goodwill find yet so I don't know what the motor will look like but this is the idea.

[Scrapper]

I bet PonderThis would have had some sort of advice to offer.

[bbqboy]

You need a rheostat to reduce speed.

[tvguy]

Older sewing machine motors are DC. DC motors used to be a better choice when you are going for variable speed.
Old sewing machine should still be easy to come by. I had one in my shop for years I saved from a sewing machine I scrapped but at some point I got rid of it.

It was the motor and the foot pedal with all the wiring. Not sure if it would be enough torque but I bet it would.

Also You didn't say what size Harbor Freight drill you had. You could simply buy a larger drill and maybe something of a better quality.

I bought a 4 in grinder at Harbor F one time for something like 10 bucks.When I tried to use it I found it was so powerless that if you tried to grind anything with any pressure at all it would just stop
After I looked closer I saw that it power was rated in WATTS.. Like 250

If you can find a Milwaukee drill I thing any size would work..... her's an example of what I just found on CL....

Drill Gun - $10 (Medford)
image 1

condition: good


Drill Gun by Milwaukee. This drill gun does not need batteries; it runs on 110. Its not pretty but its strong. Make me an offer. Even barter works for me. Please do not text me. Call only.

[chuck white]

You need a rheostat to reduce speed.

That won't work well with a synchronise motor. Their speed is dictated by the 60Hrz frequency of the line. All a rheostat or dimmer will do is reduce the power available to turn the motor. eventually you reduce the power that the motor starts to slip from being locked with the 60 Hrz. but any load change will drastically effect the speed.

How many RPM our you looking for?

[chuck white]

$7.50
http://www.halted.com/commerce/catalog/p...8651145118

$3.95
http://www.halted.com/commerce/ccp13194-...-11815.htm

[Valuesize]

Older sewing machine motors are DC. DC motors used to be a better choice when you are going for variable speed.
Old sewing machine should still be easy to come by. I had one in my shop for years I saved from a sewing machine I scrapped but at some point I got rid of it.

It was the motor and the foot pedal with all the wiring. Not sure if it would be enough torque but I bet it would.

Also You didn't say what size Harbor Freight drill you had. You could simply buy a larger drill and maybe something of a better quality.

snip....

The cheapest one. 18 V Max torque 7 ft-lbs. Too cheap? I tried my Black & Decker (5 amp) drill that plugs in the wall but it had the same problem.

[Valuesize]

Oh, I saw a couple of sewing machines at the Goodwill today. They are made to be variable speed so if they are strong enough maybe it worth the extra money they cost. ($25 as compared to $13 for a bread machine or ice cream maker) Maybe I'll go back and test how strong the motor is.

[Valuesize]

You need a rheostat to reduce speed.

That won't work well with a synchronise motor. Their speed is dictated by the 60Hrz frequency of the line. All a rheostat or dimmer will do is reduce the power available to turn the motor. eventually you reduce the power that the motor starts to slip from being locked with the 60 Hrz. but any load change will drastically effect the speed.

How many RPM our you looking for?

30 - 50.

Dang I was hoping a dimmer switch would work.

[Valuesize]

$7.50
http://www.halted.com/commerce/catalog/p...8651145118

$3.95
http://www.halted.com/commerce/ccp13194-...-11815.htm

How do I know if one of these has enough torque? I have no idea what amps, volts, watts etc mean as to whether it will turn my drum.

[tvguy]

You need a rheostat to reduce speed.

That won't work well with a synchronise motor. Their speed is dictated by the 60Hrz frequency of the line. All a rheostat or dimmer will do is reduce the power available to turn the motor. eventually you reduce the power that the motor starts to slip from being locked with the 60 Hrz. but any load change will drastically effect the speed.

How many RPM our you looking for?

30 - 50.

Dang I was hoping a dimmer switch would work.

Nah, Chuck is correct I've seen too many people hang a paddle fan in place of a ceiling light and leave the dimmer there instead of replacing it with a switch. It can ruin the fan.

[tvguy]

$7.50
http://www.halted.com/commerce/catalog/p...8651145118

$3.95
http://www.halted.com/commerce/ccp13194-...-11815.htm

How do I know if one of these has enough torque? I have no idea what amps, volts, watts etc mean as to whether it will turn my drum.

Those motors are tiny, They won't work.

[Valuesize]

$7.50
http://www.halted.com/commerce/catalog/p...8651145118

$3.95
http://www.halted.com/commerce/ccp13194-...-11815.htm

How do I know if one of these has enough torque? I have no idea what amps, volts, watts etc mean as to whether it will turn my drum.

Those motors are tiny, They won't work.

I would actually prefer having two motors, one being cordless so I don't have to rely on A/C so I can roast at a farmers market or farm stand.
If my 18 V max torque 7 ft-lb. drill won't work for much more than two pounds of beans, what numbers am I looking for if I use a rechargeable drill?

[chuck white]

$7.50
http://www.halted.com/commerce/catalog/p...8651145118

$3.95
http://www.halted.com/commerce/ccp13194-...-11815.htm

How do I know if one of these has enough torque? I have no idea what amps, volts, watts etc mean as to whether it will turn my drum.

Those motors are tiny, They won't work.

I would actually prefer having two motors, one being cordless so I don't have to rely on A/C so I can roast at a farmers market or farm stand.
If my 18 V max torque 7 ft-lb. drill won't work for much more than two pounds of beans, what numbers am I looking for if I use a rechargeable drill?

Lets figure out how much torque you need.
If the drum is empty and balanced , the torque required is small, Just enough to over come friction of the bearings.

If you only have 2 lbs of beans at a distance of 1 foot. it would only take 2 ft=lbs of torque to hold it level with the axes. I don't know the diameter of your drum but it doesn't seem to be more than two feet.

You want a rotational speed of 30 RPM or a turn every 2 seconds.
that's figures out to be a speed of 3.14 ft/sec (assuming a 1 ft radius).
so to lift from the bottom to a quarter turn (in a half second) gives an acceleration of 6.28 ft/sec^2
or about a 1/5 of g.
so 2.4 ft/lbs of torque. but that's at full speed. I think your drill 7 ft-lb is only rated at a stall.

I would say you need about 4 watts per lb at 30 RPM, 6 watts per lb at 60 RPM, for a 1 ft radius. just to equal the energy needs of lifting the weight.. multiply that by 1.5 for losses.

[Valuesize]

$7.50
http://www.halted.com/commerce/catalog/p...8651145118

$3.95
http://www.halted.com/commerce/ccp13194-...-11815.htm

How do I know if one of these has enough torque? I have no idea what amps, volts, watts etc mean as to whether it will turn my drum.

Those motors are tiny, They won't work.

I would actually prefer having two motors, one being cordless so I don't have to rely on A/C so I can roast at a farmers market or farm stand.
If my 18 V max torque 7 ft-lb. drill won't work for much more than two pounds of beans, what numbers am I looking for if I use a rechargeable drill?

Lets figure out how much torque you need.
If the drum is empty and balanced , the torque required is small, Just enough to over come friction of the bearings.

If you only have 2 lbs of beans at a distance of 1 foot. it would only take 2 ft=lbs of torque to hold it level with the axes. I don't know the diameter of your drum but it doesn't seem to be more than two feet.

You want a rotational speed of 30 RPM or a turn every 2 seconds.
that's figures out to be a speed of 3.14 ft/sec (assuming a 1 ft radius).
so to lift from the bottom to a quarter turn (in a half second) gives an acceleration of 6.28 ft/sec^2
or about a 1/5 of g.
so 2.4 ft/lbs of torque. but that's at full speed. I think your drill 7 ft-lb is only rated at a stall.

I would say you need about 4 watts per lb at 30 RPM, 6 watts per lb at 60 RPM, for a 1 ft radius. just to equal the energy needs of lifting the weight.. multiply that by 1.5 for losses.

This is the roaster. The drum is 15" long by 8 1/4 diameter. It is attached to a BBQ spit rod that sits on the BBQ with no bearings.

Thanks for "doing the math" but I don't understand a bit of it. I have no idea how many watts my drill motor has, but it appears by your math my B&D 5 amp drill is way under power so the cordless is too.

I just want to spend as little as possible so I'll see if I can find a free or cheap sewing machine first, then if that doesn't work take your info to buy a heftier drill.

Thanks again....

[chuck white]

Wow with a 4" radius, you'll need a lot less power per lb ( about a 1/3). I'm surprised that a small motor would have any issue at all.
Is there some chance something is binding. Can you turn it by hand? I suspect that drilling a screw into a piece of wood would take more torque. Can you compare the effort to turning the drum by hand (turning the shaft not the drum part) with screwing in a sheet rock screw into a pine board?
How many pounds are you putting in the drum?
Also 30 RPM seems fast. I would think 5 to 10 RPM would be more reasonable.

[tvguy]

I would actually prefer having two motors, one being cordless so I don't have to rely on A/C so I can roast at a farmers market or farm stand.
If my 18 V max torque 7 ft-lb. drill won't work for much more than two pounds of beans, what numbers am I looking for if I use a rechargeable drill?

If you could find a 12 volt motor then you could run your roaster on your car battery or a spare 12 volt battery.
You said your battery drill 18 V max torque 7 ft-lb didn't cut it.

12 volt trolling motors are easy to find and even the smaller ones are usually at least 28 foot pounds.
A 30 ft pound Minn kota is 100 bucks new and you can find them for half of that or even less . I know, I have at least five trolling motors that I've bought for a now defunct electric boat project

[bbqboy]

How much do unroasted beans weigh vs. the finished product?

[Valuesize]

Wow with a 4" radius, you'll need a lot less power per lb ( about a 1/3). I'm surprised that a small motor would have any issue at all.
Is there some chance something is binding. Can you turn it by hand? I suspect that drilling a screw into a piece of wood would take more torque. Can you compare the effort to turning the drum by hand (turning the shaft not the drum part) with screwing in a sheet rock screw into a pine board?
How many pounds are you putting in the drum?
Also 30 RPM seems fast. I would think 5 to 10 RPM would be more reasonable.

I think the drill has much more torque when you fully squeeze the trigger. I am asking it to turn my drum with about as minimum speed possible with the trigger slightly pulled using a screw clamp. As I said above, it works with 2 1/2 lbs. or less but I want to ultimately roast 5 +.

I think 20 rpm's might be OK and having a variable speed would be best of all. Thats why I tried the drill with the adjustable clamp first.

[Valuesize]

I would actually prefer having two motors, one being cordless so I don't have to rely on A/C so I can roast at a farmers market or farm stand.
If my 18 V max torque 7 ft-lb. drill won't work for much more than two pounds of beans, what numbers am I looking for if I use a rechargeable drill?

If you could find a 12 volt motor then you could run your roaster on your car battery or a spare 12 volt battery.
You said your battery drill 18 V max torque 7 ft-lb didn't cut it.

12 volt trolling motors are easy to find and even the smaller ones are usually at least 28 foot pounds.
A 30 ft pound Minn kota is 100 bucks new and you can find them for half of that or even less . I know, I have at least five trolling motors that I've bought for a now defunct electric boat project

I like this idea. Can you show me an example photo of the type you're talking about?