Your milling fixture looks like a great start for the frame parts machining Chris!

Hope the frame inflation procedure (as Kim mentioned a few posts back) goes smoothly!  Definitely want the "dirigible" setting on the compressor rather than the "blimp" one... 

This morning I got a start on trimming the frame pieces, starting with taking the shorter parts to length from the rough sawn sizes.  Then made up a holding jig for the longer pieces. I need a way to hold the long sections for milling in steps and also for drilling the patterns of holes. Holding them in the normal mill vise is fine for short lengths, but to do long notches or to drill holes accuratesly that are along a 10.6" length, the parts need to be held securely along the whole length. So, I got out a piece of hardwood and drilled/countersunk holes in it to hold it down on the mill table tooling plate:

To ensure the top surface is dead flat and level with the mill table, and to make steps for the parts to sit against to have them aligned to the long axis of the table, the top of the wood block was taken down with an end mill. Edges were left at the ends and down the sides (red arrows) to push the edges of the stock up against. The flanges left at the ends will serve as work stops to align successive parts in the same position as well.

Here is one of the side rail blanks clamped in place:

And one of the narrow side rails, clamped in place to mill a recess all the way down the length. You can see the notch on the upper right corner of the bar.

Its working out well for the initial cuts. The long bars all need to be trimmed to final lengths, and I can start drilling/tapping holes down the length to hold these narrow side bars to the wider ones. This way I can make up the tall angle shape for the lower frame perimeter, and the wide bars will extend down inside the wood bases. Here is the CAD view again to show what I mean for the shapes on the base. You can see how the cylinders sit down inside the base frame, and there needs to be room for them to swing underneath.

Thank you all for the inputs   

The regenerative pump as Per describes is an interesting concept. They are described as offering high pressures at low flow. The rotor and housing have some complicated geometry. I guess they are designed using some form of flow simulation program. The optimum number of cavities in the rotor seems to be 50 – 60. To make a pump much smaller than the current commercial offerings would be quite a challenge. Mass production using injection moulding or other additive machining would be quite easy and probably be cheaper that gear pumps as the clearances can be somewhat larger.

Peter, my cantilevered pump design was intended to simplify construction (I think many commercial pumps are of similar design). The gears should be supported by the fluid film between then and the cavity. The bearing on the input shaft needs to be able to take the forces from the driving mechanism.

Two piece or three piece is an interesting decision. A two-piece pump design, like mine, makes it easy to keep the cavities and shafts concentric and at the required separation but the face of the cavity can only be as good as you can bore it. A three-piece pump is harder to keep concentric and at the same separation unless the parts are doweled together for the boring operation.

My initial tests have been carried out with whatever is to hand. When the pump is drive by my small lathe I have no indication of the power consumed. For most of these trials the pump was connected to an injector, but did not reach enough for it to open. I fed the commercial pump from a bench power supply so I could read the voltage and current but had no idea of the speed.

I am currently trying to improve the way I make the pumps. Milling across the gears and body seems to work, but requires the bottom of the cavities to be of good finish and of the same depth (no problem with a three-piece pump). I am also considering making a rig to lap the gear teeth together based on Per’s idea of having one shaft in an excentric bush.

The ports are drilled slightly deeper than the gears to ensure that the full tooth width is in contact with the fluid.

I use commercial lip seals to seal the drive shaft, something like these:

https://oringsandmore.com/metric-oil-shaft-seals-vg-style/

I think that if the surface finish on the body and cover are good the seal should be adequate. I only had a leak there when I didn’t have a good finish, Hylomar would be my choice if there is a problem.

Viscosity will have a significant effect on these pumps. As long as the pump suction is above the vapour pressure of the fluid (a problem with petrol/gasoline) the cavities will be filled so the pumped volume will remain constant. The leakage will be reduced with a higher viscosity fluid so the theoretical maximum pressure will increase.

Do they have Craigslist there?

Three Austin 7's? "As seen on TV" https://www.mathewsons.co.uk/, they have even been heard of in New Zealand

Pete