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Black Forest
04-12-2015, 08:52 AM
If I can't get this treadmill motor and boards to work then I will use a mechanical drive for my welding positioner. So I will need a variable speed transmission.

I have several gear reduction options already.

So what would you all suggest for a variable speed drive I could build? One option I thought of was a smaller rubber type wheel running on the face of a larger flat wheel.

The more to the outside it is positioned the slower the table would turn. Move it with a lever to the opposite side of the flat wheel and the table would reverse.

Keep in mind this will not have to have a broad range of speeds. The table needs to go from .5 rpm's to maximum 10 rpm's.

gvasale
04-12-2015, 09:00 AM
Something like a snowblower uses. Maybe even cobble an old snowblower for parts.

Black Forest
04-12-2015, 09:03 AM
Something like a snowblower uses. Maybe even cobble an old snowblower for parts.

I googled snowblower transmission and got not much. Do you have a sketch or picture of what you are talking about?

gvasale
04-12-2015, 09:07 AM
I can get one from a parts blow up, but it might be faster for you to go and do a web search for Ariens then look for snow blowers model 924050 should bring you right in. Look in the tractor file.

Black Forest
04-12-2015, 09:14 AM
I can get one from a parts blow up, but it might be faster for you to go and do a web search for Ariens then look for snow blowers model 924050 should bring you right in. Look in the tractor file.

I went to youtube and found lots of videos on what you mentioned. That is what I was referring to in my original post. Thanks.

gvasale
04-12-2015, 09:17 AM
Diagram is cluttered. On the left is the driven pulley from the engine. Nestled on the far right is its counterpart, looks like somewhat circular fins on it. Below to the right is the disk which slid from the center to the rim of the driven flywheel givin variable speed and even reverse rotation. Not much simpler in transmissions, unless you can scrounge up an old Peerless gearbox used on lawn tractors. Those had from 3 to 5 or 6 speeds.

kitno455
04-12-2015, 09:22 AM
You should be able to find a scooter repair shop around, and get a complete CVT from one. You would have to add a manual control instead of using the variator, but the rest of the parts would be useable as-is.

A.K. Boomer
04-12-2015, 09:32 AM
what about a typical three speed bicycle hub? built a pulley around it and drive it by a belt, shift on the fly if and when you want?

Black Forest
04-12-2015, 09:37 AM
what about a typical three speed bicycle hub? built a pulley around it and drive it by a belt, shift on the fly if and when you want?

It needs to be infinitely adjustable. I would rather adjust the table than have to adjust my welding style, speed, amps, etc. to fit the speed of the table.

A.K. Boomer
04-12-2015, 09:40 AM
hmmm - then your idea sounds about as simple as it gets, spring loaded and on a couple of linear slides, you would have to have it running to change speeds but that's how most stuff mechanical is going to be.

Lew Hartswick
04-12-2015, 10:07 AM
One of the riding lawn mowers used the "wheel and disc" drive for years (Maybe Snapper). So I think it would have the right order of magnitude capability. :-)
For the 20:1 ratios youre talking about the wheel will have to be pretty good size to have the needed size "inner" track. The mechanism does have the nice
reverse capability of the same speed.
...lew...

mickeyf
04-12-2015, 11:31 AM
I once saw some sawmill machinery (what you'd probably call "antique") that used exactly this technique - a wheel riding on a spinning disc mounted at at 90 degrees to it. If I recall, rather than being limited to one radius of travel the wheel may have been able to traverse beyond the axis of the disc, so that the rotation of the wheel was reversed after slowing to zero. That may even have been the main purpose.

A.K. Boomer
04-12-2015, 12:35 PM
You can make the variable pulley type system (like a snowmobile) also called a "torque converter"


but instead of it being load and RPM activated you have a lever that controls both the growth of one pulley whilst at the same time shrinks the other and visa versa,,, depends on how much range you would need as it does have it's limitations --- but then again snowmobiles can launch off the line and get well into the triple digits so there is some range for sure...

Daminer
04-12-2015, 01:58 PM
I think you're looking for a "reeves" pulley system. Here are some pics:

https://www.google.com/search?q=reeves+pulley&biw=1366&bih=667&tbm=isch&tbo=u&source=univ&sa=X&ei=17EqVZGrG8SkNsrcgJAJ&ved=0CD4QsAQ

firbikrhd1
04-12-2015, 03:21 PM
As Lew states, Snapper does indeed use a wheel and disk system than will give variable speeds. If you could be satisfied with a non variable transmission with gears you might adapt the transmission from an old Honda ATC 90 or 110 or Trail 90 to a speed reducer. They have 4 speeds plus a high and low range and an automatic clutch. I bought one years ago to use on a bandsaw but never got around to the conversion. It's on the list but these days with DC motors and decent drives reasonably priced I may never use it for that.

EddyCurr
04-12-2015, 03:41 PM
I think you're looking for a "reeves" pulley system. Here are some pics:

https://www.google.com/search?q=reeves+pulley&biw=1366&bih=667&tbm=isch&tbo=u&source=univ&sa=X&ei=17EqVZGrG8SkNsrcgJAJ&ved=0CD4QsAQI agree that a Reeves-type Vari-Speed Pulley transmission
is what the OP may be interested in.

One difference between vehicular and industrial applications is
that vehicle applications are designed to vary speed automatically
in relation to the engine RPM and load. For industrial applications,
input speeds are typically fixed by motor RPM and output speeds
are adjusted manually.

The industrial pulley transmission may consist of one variable-speed
pulley assembly driving a fixed pulley (simple), or of a pair of drive
and driven vari-speed pulley assemblies (compound). The former
(simple) arrangement requires some kind of provision for adjusting
distance between the drive and driven pulleys to allow for belt
tension take-up; the latter (compound) arrangement automatically
adapts to maintain proper belt tension when properly configured.

Some Reeves Vari-Speed technical literature (http://www.master-pt.com/images/pdf/PULLEY_MPT.pdf)

Edit: I meant to include a remark about the oval 'set' that a belt
for a Reeves pulley arrangement customarily adopts, assuming it
doesn't start out with such a set from new. For power transmission,
the oval has little if any influence. However, it might prove to be
a detriment in a welding positioner application unless perhaps there
is a device downstream that stabilizes the eccentricity of the oval
belt. A worm drive or brake or ...

Regarding the friction disk style of transmission/clutch. These are
widely used today on snowblowers. One version was developed by
John W. Lambert (http://en.wikipedia.org/wiki/John_William_Lambert), credited with constructing the first automobile in
America in 1891.

.

The Artful Bodger
04-12-2015, 03:51 PM
Is the requirement for just one revolution or do you need continuous?

I know you are a great man with hydraulics so how about a rack being slowly moved by a hydraulic cylinder? It could be a rack and a gear or a length of roller chain around a sprocket.

Such an arrangement is something that could be driven by water pressure from the garden hose.

Don Young
04-12-2015, 09:43 PM
The Reeves type of drive has been used on riding lawn mowers made by MTD and others for a long time. It uses normal Vee belts and is pretty rugged and inexpensive. It has two fixed pulleys for input and output and a variable pulley between them.

Edwin Dirnbeck
04-12-2015, 11:12 PM
Harbor freight has a very good and cheap variable speed speed high power buffer. This buffer has an excellent closed loop feedback speed control that really maintains the speed even when you bear dowwn on it . It is way better than your typical "variable speed power tool".You can get these on sale for about $35,the speed range is 200 to 3300 rpm and draws 10 amps.Just try one ,if you dont like it ,return it.Good luck ,Edwin

Black Forest
04-12-2015, 11:56 PM
Harbor freight has a very good and cheap variable speed speed high power buffer. This buffer has an excellent closed loop feedback speed control that really maintains the speed even when you bear dowwn on it . It is way better than your typical "variable speed power tool".You can get these on sale for about $35,the speed range is 200 to 3300 rpm and draws 10 amps.Just try one ,if you dont like it ,return it.Good luck ,Edwin

It is about a 7000 mile drive to the nearest HF for me. With fuel and all that makes the unit a little expensive.

becksmachine
04-13-2015, 12:51 AM
I would think that a suitably heavy worm drive gearbox driven by a VFD would be the way to go.

Am I missing some stated requirement?

Dave

The Artful Bodger
04-13-2015, 12:54 AM
It is about a 7000 mile drive to the nearest HF for me. With fuel and all that makes the unit a little expensive.

Have they got the Bering Strait Bridge open yet?
https://www.asme.org/getmedia/ad0fc9c6-8f21-4008-90ee-3db3c3929533/Connecting_Two_Continents-Arctic-01-280x225.aspx

oldtiffie
04-13-2015, 01:07 AM
Why not use hydraulics?

Black Forest
04-13-2015, 01:23 AM
Why not use hydraulics?

That would be too easy! I wanted to try to learn something on this project. But I am definitely leaning in that direction.

Black Forest
04-13-2015, 01:26 AM
I would think that a suitably heavy worm drive gearbox driven by a VFD would be the way to go.

Am I missing some stated requirement?

Dave

I would be a little worried about the High Frequency start while TIG welding playing havoc with the VFD. It might not be an issue but it definitely is something to consider.

big job
04-13-2015, 06:26 AM
I'm almost sure Keith Ruckers vidio i think it was the plainer. With the disk drive, its the simplest motion transfer on the planet. Also Tom Lipton has a vidio
on a machine forgot what, that has that. fast slow stop reverse with one hand lever slick....