Lube pump plunger size

[grege]

I have started the Lubricator for my A3a


I haven't been able to find the .1" stainless rod specified for the plunger, and had been planning to just use 3/32" as I have that size and a reamer for it.

Now that I'm ready to make it I've started questioning the choice and wondered what other builders have done?

I did find steel drill blank that meets the specs, and can get the single reamer. It seems that in an oil pump chances for corrosion would be slim, but I suppose if the checks failed and steam backed up it could get wet.

To use the 3/32" I could do one of the following adjustments:
-Use fewer divisions on the ratchet- about 35 instead of 40 seems to get the same volume of oil. May need a shorter lever too as I've already made the eccentric.
-Increase the stroke- roughly by .04" with a slightly larger crank wheel and more volume in the pump body below the inlet holes.
Either one I need to draw up more accurately to get a good dimension.

Is it all that critical? Or will there be plenty of oil either way?
Thanks for any comments.

[dickr]

I would think the drill rod would work fine. Turn the end down then harden it. That makes it much tougher to corrode. I really don't think it would make that much diff. (.093) or(.1) But then that's just a seat of the pants guys opinion.
Really nice looking parts !!!

[phutcheson]

Hi Greg ...

Question for you or any one else that may have changed the design of the Lubricator.

What did you actually end up doing?

I'm just about ready to make the Pump Body and will be using 3/32" Plunger.

With about 12% less oil, I am concerned that there may not be enough oil pumping to the cylinders.

Like your suggestion it would not be much of a change to bring
up the volume in the Pump body. I like the idea of increasing the Crank size and add length to the Plunger to increase the volume (would also have to reduce the top a little so that Plunger would not hit Pump body).

By the way ... did you notice that the stroke is given as .25 in Fig 21-10, but 15/64" in Fig 21-1 ? That represents about a 6% reduction in oil.

Thanks,

Pat H.

[Ed Hume]

I can't tell exactly what I did from my notes but I have a 0.100" reamer in the drawer. You can buy 0.995" drill rod or 0.100 stainless rod from Small Parts Inc but I do not have any rod of that size leftover so I think I turned and polished the rod from larger stock.

You can buy 2.5mm "precision shafting" from McMaster Carr along with a 2.5mm reamer, so that is an alternative.

I think you will do fine with 3/32" and you should not worry about the 12%. I have made lubricators for 3 locomotives now, and the oil flow obtained has been very generous. In fact, I shortened the crank throw on my Heisler to reduce the flow - this is your easiest adjustment. If you change the ratchet wheel you have to modify other parts.

If you have a rotary table that you can position vertically, you can do a better job cutting the ratchet wheel on the mill than on the lathe. Make a sandwich of the wheel stock with brass around it to have a clean cut. You can use CAD as follows to determine the cut. Divide the circle into 40 pies. Draw a right triangle tooth in the pie whose smaller side is the .04 tooth height. Rotate the pie so that the long leg of the tooth is horizontal and the 0.04 leg is vertical. Your cut edge will be below the top of the wheel by 0.0292" and off the center of the wheel by 0.0754". You cycle on rotating the table 9 degrees and moving the cutter through the tooth and out of the way.

Regards,
Ed

[phutcheson]

Ed ...

Thanks for the input and the suggestion on the ratchet wheel. Like that method should make things easier.

Think I will look into what Small Parts have ... may go that route or then again I have what I need using 3/32" SS. Easy to modify the Plunger and Crank. Will leave the ratchet alone though. Decision and more decisions.

Thanks again.


Pat H.

[grege]

Hi Pat.
I used a .100" reamer and .0995 drill blank, not drill rod.
It was already hard, as I found out when I tried to turn down the end to fit the little bronze bit on top.
It made for a beautiful fit in the pump body.
It is plain steel, not stainless, but as its bathed in oil I'm expecting that it will do just fine.
Greg

[phutcheson]

Greg,

Thanks for the response.

I went to McMaster Carr site and ordered a .1000 reamer and the drill blank. I'll find out how hard it is to cut to size and then turn down the top. I agree ... no worry about rust in a oil bath.

This should be fun.


Pat H.

[grege]

I don't really remember the specifics, but I likely only reduced it to 3/32".
All you really need is a square shoulder and a close fit to the bronze piece.
Have fun!

[alexbarb]

I think its a technical problem So you should consult a good technician..I think there you could get the best solution easily.

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