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making new sliding pump vanes

I'm rebuilding several Blackmer pumps that are used for diesel fuel. They have outlets of 2.5" and pump about 70 gallons per minute at 375 RPM.

The pump housings are cast iron. I need to replace the pump vanes. The vanes slide in a rotor that spins in an ellipitical housing.

The original vanes are made from a plastic molded composite material that looks just like bondo. The pump company charges over $300 for a set of 6 vanes (rectangular about .375 thick x 4" long x 1" wide,) so it might be more economical to make my own.

I've been considering canvas phenolic, delrin bar stock, or aluminum flat stock. I figure I can mill a batch of these vanes in short order.

Any comments or suggestions appreciated on the materials selection.

Tony

Reply to
Tony
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The vanes in small air motors are often linen phenolic, so as long as phenolic is compatible with diesel I'd think it would be a good choice.

Reply to
Ned Simmons

Ned,

I made vanes for a DoAll bandsaw blower from canvas phenolic material. There were 4 vanes about 2'x2' My stock machined rough and fuzzy so I made the vanes a little oversized and lapped them dry with fine wet or dry paper on a flat surface. I got a nice close fit in the rotor slots and the vanes turned out dark and shiny. They worked fine.

Your 6 vanes are bigger so it would be more work but it can be done.

Regards, Charlie

Reply to
chlessig

Coincidentally, I've also had the air pump on my 1948 DoAll ML apart. It was several years ago, but as I recall the vanes appeared to be some sort of carbon or graphite composite. The pump wasn't working because the dust from the vanes wearing was interfering with the vanes' fit in the rotor. I cleaned it up, put it back together, and it's still working fine. Pretty good for a 60 year old saw.

Reply to
Ned Simmons

One thing i've noticed over time in rebuilding these pumps is that grit and metal filings seemed to get embedded in the composite plastic vanes (probably debris that got passed the strainer) and scores the pump housings.

I was leaning towards aluminum vanes since I think they are less likely to do damage to the cast iron housing. Brass or bronze might be even better/longer lasting.

Tony

Reply to
Tony

According to Tony :

Note that when lapping, the harder material is what is cut, because the abrasive embeds in the softer material. So based on that, you would want steel for the vanes.

But something like graphite which does not tend to accept things embedding in it, but which wears to conform to the contour of the housing would perhaps be the best choice.

Good Luck, DoN.

Reply to
DoN. Nichols

The air pump vanes in my "torpedo heaters" use graphite vanes

Gunner

Reply to
Gunner Asch

Year ago I spoke to some people at Precision Scientific about why their vacuum pump vanes went from graphite to metal. The reason I was told was graphite allowed for a less accurate initial fit, and would wear into place, but that wasn't a problem these days and metal vanes that last longer if they're made to the right size the first time.

Reply to
Cydrome Leader

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