Swifty's build of Howell V4

[Swifty]

I managed to finish the oil pump today, as suggested on the drawing, I used some carbide shafting for the pins on the gears. They were broken cutter shanks that I had kept, the long shaft runs on 2 bearings and also 2 "O" rings, "O"rings can be very hard on shafting and wear it away. The smaller carbide pin came out of a longer piece, I just used the corner of the diamond cup wheel to score the outside as much as I could, then snapped it with a pair of pliers. The ends were cleaned up to size in my cutter grinder.



One gear has been loctited to the long shaft, and the short shaft has been loctited in the top plate. I'll give it 24 hours to cure properly and then do the final assembly.



Just for something different for a change, I cut up the brass bar that will be the radiator fins, bored a hole in a scrap block and tapped M8 in the side to hold the bars for facing. The brass is all out of the same bar, and very consistent in size across corners, the sides are all within .001" of centre, I'm not sure if I will use the same fixture to cut the fins, I already have another idea forming in my mind, will see what happens.



Paul.

 

[Charles Lamont]

That is some very fiddly work. But, and I am probably being daft here, it looks to me as though the inlet and outlet ports in the pump body are drilled right through. If so, surely it will just recirculate?

 

[Swifty]

Hi Charles, I can only assume that the oil pump is a tried and tested design, there is a hole drilled through the bottom half of the pump right where the 2 gears mesh. Part of the hole is left in the bottom as you will see in the picture. The gears are a very close fit in the bores, so I assume that the oil takes the path of least resistance, I'm led to believe that they get good oil pressure with this pump.

I did some more work on the radiator fins, I'm fortunate that I have a cutter grinder that takes a 3/8"square 5C collet, so I can hold the HSS toolbits to accurately grind them to size. So, I made my .040"wide grooving tool with all the correct relief angles, then mounted it in the lathe toolpost and indicated the side so it was perfectly square, after picking up the edge, I started to cut a few grooves. One thing that became immediately apparent, was that the fin that was left pushed over as I was cutting the groove. I had started from the tailstock end, working my way along towards the headstock. After several fins did this, I moved along as far as I could towards the headstock, and started to work my way back to the other end, this did improve things a lot, not perfect, but much better. Maybe its stresses in the material causing this. I did find out something else whilst cutting the fins, I don't have a readout on the lathe, so I'm going to have to clamp down a digital vernier to the bed to get correct pitching between the grooves. the hand wheel is just not good enough. There was a recent thread on doing this, so I will look it up.

Here's a photo of the test fins, I had straightened up most of the fins using a feeler gauge. It may be just as well that I have 3 meters of brass for the fins, I may need it all.



Paul.

 

[wirralcnc]

Paul
When I did this radiator I had the same problem with fins bending.
I actually used two 1/16" blades. Ground each blade to give me width of one groove and half a fin. Then ground the front to .040" wide and stuck the blades back to back in a holder. Works perfect. One blade cuts the other just supports the previous fin.
Robbie

 

[GailInNM]

Paul,
A "T" type cutoff tool works very well for this as it has a greater side relief angle. If you can grind a concave in the top of the tool this also helps. Both items help reduce the side pressure by curling the chips away from the sides of the cut.

For your application a standard P1N cutoff blade works well as it is 0.040 wide. Occasionally you will find a manufacturer who grinds the concave in the top of these blades, but most are a flat grind top. You do have to shim the bottom side of the blade to make it stand vertical in a regular blade holder or make up a stepped blade holder.

I recently cut 0.03 wide fins with 0.03 grooves in 6061 square alumnium. 5 pieces with 30 fins on each piece with no bending. I was using a P1N blade that I had ground down to 0.030 wide and a flat top.
Gail in NM

 

[Swifty]

Thanks for the advice Robbie and Gail, I will play around with it a bit more soon. I don't think that the chips are causing the problem, as its brass that I'm turning and I am getting typical hard brass fine swarf coming off.

Paul.

 

[Charles Lamont]

I can only assume that the oil pump is a tried and tested design, there is a hole drilled through the bottom half of the pump right where the 2 gears mesh. Part of the hole is left in the bottom as you will see in the picture.

I thought that was what I could see and it means the inlet and outlet sides of the pump are directly connected, which is 'wrong'.

The gears are a very close fit in the bores, so I assume that the oil takes the path of least resistance,

That is precisely what worries me. The oil will be carried round from the inlet in the gear tooth spaces and squeezed out into the outlet by the meshing of the gears, good so far, but then it will do as you say - and go along the channel behind the gears back to the inlet.

I'm led to believe that they get good oil pressure with this pump.

Well if it works, it works, and so much for the logic.

 

[bigrigbri]

For the miter gears have you tried HPC gears here in the UK.
If you did machine them yourself a running in oeriod in a jig at the set depths using a little metal polish to allow each gear to bed into each other.

 

[wirralcnc]

Paul
Few photos of the tool I made and the radiator it produced.
Robbie

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[Swifty]

Thanks for all the advice guys, I'm away from home at the moment and accessing the forum with my phone, I will respond more in a couple of days.

Paul.

 

[Gerhardvienna]

Hi Robbie
Nice job, well doneThm:
What material did you use for the cutters?
Regards
Gerhard

 

[wirralcnc]

Two hss 1/16" blades from ebay.
Robbie

 

[Lesgsy]

I thought that was what I could see and it means the inlet and outlet sides of the pump are directly connected, which is 'wrong'.

That is precisely what worries me. The oil will be carried round from the inlet in the gear tooth spaces and squeezed out into the outlet by the meshing of the gears, good so far, but then it will do as you say - and go along the channel behind the gears back to the inlet.

Well if it works, it works, and so much for the logic.

Once drilled
I had to fill the centre with soft solder to get mine to Give a good pressure !

 

[Gerhardvienna]

Two hss 1/16" blades from ebay.
Robbie

Thank you, must look for this in Ebay Austria or Germany! The fins look really good, I need that for my Saurer-engine oil and water cooler.
Regards
Gerhard

 

[wirralcnc]

Gerhard
They were actually german made hss blades. Think they were around £5 for the two. tried alsorts to stop fins bending. But only the two blade tool did a quality job.
Robbie

 

[Swifty]

I'm back from a couple of days break, first job was to order the miter gears for the distributor drive. Ordered them from SDP/SI in the US, just on A$50 the pair delivered. Now I have to concentrate on the fins for the radiator.

Paul.

 

[Swifty]

Thought that I would do an easy part, so chose the pulley, collet and nut for the oil pump. The thread on the collet is 1/4 - 32, I have a tap to suit for the nut, but had to screw cut the collet thread. All was straight forward, the 5C collet blocks came in handy for the nut flats and for holding the collet for slitting.

The hole circle function on the readout makes it very easy to pitch out the holes in the pulley. The drawing calls for these holes to be reamed, no reason for it, so I just drilled to size.




Paul.

 

[gus]

Your workmanship is top class. The Oil Pump looks great. I am still struggling with mine.

 

[Swifty]

Just be patient Gus, rushing makes mistakes, just think about things before you act and you will be OK.

Paul.

 

[jimjam66]

That's an interesting approach to holding the pulley - seems more complex than necessary? Still, you made a fantastic job of it!