SB 9A Cabinet underdrive lathe

[mattthemuppet2]

thanks Brino, that's the one

here's my DP

Treadmill Motor Conversion On A Walker Turner Drill Press

alright, next project on the list - adding a variable speed treadmill motor and tach to my WT drill press which also doubles as a sort of mill. It currently has a 1/3hp motor with 5 step motor>intermediate>spindle pulleys to give 250-900rpm and 3000-5000rpm. Changing belts in the lower range...

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mill

Treadmill motor conversion for a Grizzly 6x26 knee mill

I bought this second hand last year and it's awesome (1st proper mill!), but I've been spoilt by the variable speed treadmill motors on my lathe and drill press, so I've been waiting awhile for the opportunity to add a treadmill motor to my mill. The 3 usual challenges are 1. how do I stop the...

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and current lathe

Atlas 618 Treadmill Motor Install

Hi all, this is a summary of my recent project to install a treadmill motor on my Atlas 618 (see http://www.hobby-machinist.com/threads/wiring-up-a-treadmill-motor-i-know-i-know.37159/ for the full experience!). It got a bit lost in that thread and Nels thought it would be worth posting it here...

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though that's been through a fair few changes since

 

[ottrunner]

ok, 2.75 hp treadmill motor in hand, 4000 rpm.
The motor I took off was 3/4-1725 and had a 2.5 and 3 inch pulley opposite a 10 inch and 9 inch pulley

the original at max rpm would have been turning at 430 rpm on the 3/9 and 575 on the 2.5/10
The treadmill has a 1.5" pulley, on the 9 it would run 667 on the 10" 600.

Not terribly far off and I can install an rpm gauge to ensure I don't run it too fast. I think a serpentine style belt will work just as well as the old v groove did. The pulley on the motor was v groove but the lathe side is flat.

I believe I need a 38" serpentine belt, I'm also going to get a cheap dc controller and do away with the treadmill speed controller.

 

[ottrunner]

Question:
I have 2 headstocks. The original is the "high speed" model (I have read) where the bearing is grooved. The other, no groove.

The original grooved headstock does have some marks, scoring. Not the second one, it seems perfect.

Which would you go with?

 

[mattthemuppet2]

I think your numbers are crossed - should be 575rpm at the countershaft for 3/9 (3:1 step down) and 430rpm for 2.5/10 (4:1 step down). What are the ratios between your countershaft and spindle pulleys? Either way, you won't be running at full speed all the time, I typically do most of my work between 1/3 and 2/3 speed.

I'd go with the high speed headstock as long as you can get the spindle to within the correct amount of deflection and it doesn't overheat.

I would also caution against using a cheap DC controller. Some people have reported success (eg. RJSakowski), while others have not. A guy I knew used a cheap amazon PWM signal generator with his MC2100 treadmill controller and blew the controller up within a day. KB drives are good and you can get enclosed versions (Pentadrive) - UlmaDoc on here uses alot of them. Original MC drives are also very good, but the newer ones (MC2100) need a little extra work. My setups have been dead nuts reliable in the years that I've had them, other than some cheap switches (tip, buy the good switches from Amazon), and that's what I'd aim for.

 

[ottrunner]

The countershaft and spindle pulleys are typical south bend 9". At this moment I have yet to measure them as I figured I'd go with the center and use variable speed to do the rest.

I have a lot to read in regards to dc speed controllers it seems. I did rob the treadmill of it so I do have that option but the treadmill did have a 3-second delay which I would have to figure out how to work around.

My hope is to get the motor to spin as fast as possible while having the spindle turn no more than it should at max-rated speed.

I will take your advice and go with the high-speed headstock. It does have some scoring but would likely last me 100 years as I'm not much of a machinist (although I do hope to pick up the hobby and partake at it for however long I have left...lol). I had intended to sell one of the headstocks but I'll keep it as a replacement if needed.

Thanks for the input Matt.

 

[ottrunner]

Just to review: Take this over a perfect headstock that doesn't have the high-speed grooves?

 

[ottrunner]

My memory...serves me late every time. If you notice on this headstock the casting at the top of the photo is broken, looks like someone might have given it a wee tap.

that broken off bit might allow metal, dirt, what have you, enter and run down into the oil passage. I believe that was the reason I was going against it.

Thoughts, opinions?

 

[mattthemuppet2]

I'd go with the other one then, just keep it well oiled and don't over speed it for very long.

As for the spindle/ countershaft pulley ratios it's best to think of each giving you a speed range. My lathe didn't come with a countershaft, so the pulleys that I'll be making will give me ranges of 500-1500, 250-850 and 150-500, give or take. There's a large degree of overlap but you'll find that there's a sweet spot for any given operation. I'll probably spend most of my time in the middle pulley, but I know from experience that I'll be using the ones on either side fairly frequently, plus the back gears on the odd occasion.

The easiest and usually cheapest drive to go for is an MC60/65. Super easy to set up, easily modded to avoid the "return to zero speed on start" issue, but might struggle a little if you really tax the motor. That doesn't happen much on my lathe, but it does happen fairly frequently on my mill. Next is the MC2100, can provide the full juice for a 2hp motor but requires an external PWM source for controlling speed (I'll be using an Arduino). For more money but less hassle, KB DC drives are really good. Never used one myself, but they're highly recommended.

Or use the one you have (free!) and see how it goes, plus whether or not it'll p!ss you off enough to want to change it

 

[ottrunner]

I'm still here!
I think I will attempt the high-speed headstock, if it fails I'll swap out for the other.
I have the treadmill motor installed and went with the controller attached.
My hold up right now is the rebuild kit, the first went from USPS to China, the second is expected next week.
My 3d printer isn't a workhouse at boxes.

 

[mattthemuppet2]

looks great to me, good looking motor and a neat enclosure for the drive. I'd recommend a reversing switch though - you won't need it often, but if you ever want to thread metric it'll be essential. Also if your controller needs you to turn the speed to zero everytime you switch it on (some do, some don't) then the reversing switch allows you to turn the motor off without turning the controller off, so the motor starts again at the same speed. I have that on my drill press, bit of a pain but less than having to reset the speed everytime I stop the motor.