Author Topic: 1/4 horse variable speed suggestions needed  (Read 2723 times)

Offline sshire

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1/4 horse variable speed suggestions needed
« on: June 27, 2015, 12:34:00 PM »
The 1/4 horse is going to (hopefully) run a sewing machine.
Any thoughts on a variable air pressure device for speed control. Foot operated, of course. I've seen many foot controlled air valves but they all seem to be on/off.
I'd rather machine it myself,if possible. That however, isn't a deal breaker.
Best,
Stan

Offline steamer

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Re: 1/4 horse variable speed suggestions needed
« Reply #1 on: June 27, 2015, 01:03:59 PM »
I'd try a spool valve like used on governor assemblies....

Dave
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Damned ijjit!

Offline cheepo45

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Re: 1/4 horse variable speed suggestions needed
« Reply #2 on: June 27, 2015, 11:12:20 PM »
How about a ball valve attached to a foot pedal?
cheepo45

Offline Dave Otto

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Re: 1/4 horse variable speed suggestions needed
« Reply #3 on: June 27, 2015, 11:59:50 PM »
Hey Stan

Did you miss this little beauty at Coolspring? Two cylinder water powered sewing machine motor; check out the foot pedal.

Dave

Offline sshire

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Re: 1/4 horse variable speed suggestions needed
« Reply #4 on: June 28, 2015, 12:12:22 AM »
Can't imagine how I missed that. I was sure I'd seen all 234,628 engines.
I'm leaning toward a spring loaded spool valve with a cam at the foot pedal to press the valve rod. Nothing like excess.
I'm absolutely still open to suggestions as I won't get to that until the fettling and titivating are completed.

Best,
Stan

Offline kvom

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Re: 1/4 horse variable speed suggestions needed
« Reply #5 on: June 28, 2015, 01:17:43 PM »
I'd lean towards the on-off option.  It's more important to be able to stop the machine precisely than to vary the speed greatly.  One thing to determine is how much torque the engine exerts when pressure is removed, and how long it takes to stop.

Offline Jo

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Re: 1/4 horse variable speed suggestions needed
« Reply #6 on: June 28, 2015, 01:46:26 PM »
When you use a sewing machine you start very slowly to make sure it is following the right line/both threads have being picked up, you then speed up along the straights and slow down towards the corner so that you can manipulate the material and get the stitching to follow the appropriate line.

You also need to be able to operate the powered machine by hand.

Jo

Usus est optimum magister

Offline sshire

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Re: 1/4 horse variable speed suggestions needed
« Reply #7 on: June 28, 2015, 03:13:00 PM »
I learned to sew from my Grandmother on a treadle machine.
Jo is right on as far as having speed control.
The interesting thing about the treadle Singers is a 2" diameter knob on the hand wheel. ⅛ turn disengages the belt pulley and it free wheels so that the machine can be threaded, etc without the need to shut off power.
I really believe that variable speed is necessary. Not that I'm going to do any serious work with this setup. It's primarily to answer the "but, what does it do?" questions.
Best,
Stan

Offline Jasonb

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Re: 1/4 horse variable speed suggestions needed
« Reply #8 on: June 28, 2015, 03:16:25 PM »
I wonder if this is the right way to vary the speed. Its going to be hard to start the engine with low pressure/steam flow and it won't run smoothly.

If you look at that first illustration you posted in your other thread there is a weight hanging off the back of the table, I would think this tensions the belt and the foot pedal lifts the weight and in effect gives a slipper clutch, there is no signs of any other connection to the engine apart from the belt.

Offline sshire

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Re: 1/4 horse variable speed suggestions needed
« Reply #9 on: June 28, 2015, 03:48:36 PM »
Only having to lift a weight would certainly simplify matters. Once I get the engine and the Singer belted together that is the first thing I'll try.
Best,
Stan

Offline Jo

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Re: 1/4 horse variable speed suggestions needed
« Reply #10 on: June 28, 2015, 04:39:19 PM »
You still need good slow speed control on a sewing machine otherwise you will end up with a needle through your finger  :paranoia:

Jo
Usus est optimum magister

Offline Jasonb

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Re: 1/4 horse variable speed suggestions needed
« Reply #11 on: June 28, 2015, 04:44:10 PM »
If you get the slipper action right the speed will be controlable right down to snails pace which will be easier than trying to run a steam engine at very low revs while under load