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Post by racket on Jul 18, 2018 20:47:40 GMT -5
Hi Guys A bit more work done on the freepower stage , I had to first make up a mounting jig to fit the part to so that the whole could be rotated in my rotary table on the mill so that I could cut the 3 X 30 mm slots for the "spiders" 8 legs that will support the outer ring that will be part of the wheel shroud and mount for the NGV . I went for 8 legs as 8 can't divide into the 30 wheel blades , so no chance of "phasing"  Cheers John |
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Deleted
Joined: January 1970
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Post by Deleted on Jul 19, 2018 3:31:29 GMT -5
Hi John
Its coming together, going to be a real strong unit :-)
All The Best
Andy
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Post by racket on Jul 19, 2018 4:12:34 GMT -5
Hi Andy
Yep , I'm trying hard to keep weight down whilst still maintaining strength, so everything in stainless, the mounting flange is ~10 mm thick , the centre tube is ~5 mm , the spider legs ~3 mm , the "rim" will be fairly thick at ~6mm where the legs join , but the rest of it will be ~1.5 mm for the wheel shroud, I'm hopeful of keeping total weight of the freepower/gearbox under 20 Kgs , don't want to weigh down the kart ;-)
Cheers
John
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Post by enginewhisperer on Jul 19, 2018 6:54:06 GMT -5
it looks like a small part until you notice the size of the cut off wheel  |
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CH3NO2
Senior Member
Joined: March 2017
Posts: 455 
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Post by CH3NO2 on Jul 19, 2018 15:34:34 GMT -5
Hi Andy ... I'm hopeful of keeping total weight of the freepower/gearbox under 20 Kgs , don't want to weigh down the kart ;-) Cheers John You're building another cart?  |
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Post by racket on Jul 19, 2018 17:32:33 GMT -5
Nope , no kart for me .
LOL............I might get into it, but I doubt I'm flexible enough to get back out, its a bummer getting old :-(
The gearbox/freepower is being made for kart application with its 40 mm through bore on the output shaft ..........how, when , where it'll be used is "up for negotiation" ;-)
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Post by enginewhisperer on Jul 19, 2018 18:22:42 GMT -5
putting my hand up for death kart testing. I do have a kart frame and a 40mm axle |
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Post by racket on Jul 19, 2018 20:05:11 GMT -5
Hi Andrew
LOL...you may need to "take a number" and join the queue , it'll need at least an 100mm inducered gas producer to "fill" the NGV and wheel.
I'm just hoping my health hangs out long enough to finish it within a reasonable time frame, I should get most of the work done this winter but once the weather warms up I'll probably have to put it aside until next year .
Cheers
John
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Post by enginewhisperer on Jul 19, 2018 20:34:02 GMT -5
fingers crossed! I can supply an air conditioner for your shed if it helps |
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Deleted
Joined: January 1970
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Post by Deleted on Jul 20, 2018 0:41:35 GMT -5
Nope , no kart for me . LOL............I might get into it, but I doubt I'm flexible enough to get back out, its a bummer getting old :-( The gearbox/freepower is being made for kart application with its 40 mm through bore on the output shaft ..........how, when , where it'll be used is "up for negotiation" ;-) Hi John Once your in a Kart with that kind of power on tap, would you want to get back out..... going to be an interesting machine to play with... and not just in a straight line :-) All The Best Andy |
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Post by racket on Jul 25, 2018 22:30:57 GMT -5
Hi Guys Bit of an update . The test stand mods have been completed, new shroud on the exducer in the "big" jetpipe, new heavy duty battery isolation switch , new heavy duty starter solenoid and to complete the system , 50mm2 cabling ............static testing produced ~1,000 extra RPM , things are looking good for the next test run , probably early next week weather permitting . On the freepower front , I've machined up the wheel shroud/main outer mounting ring from a short length of 8" Schedule 40 304 stainless pipe , thick stuff , eventually had to shrink fit it onto a "backing plate" to allow machining out as I couldn't hold it firm enough in the chuck jaws , gave it ~0.004" - 0.1 mm of inference fit onto the backplate , worked a treat , but had to heat it to ~250 C in the kitchen oven to get them apart . The bits.  With wheel dropped into place , 1mm diametric clearance over the 212 mm dia wheel  Because the "mounting ring" has the wheel shroud , I had to remove the wheel shroud from the 4th stage NGV ,.......... now that was "hard shitium" to machine off............the OD was machined down for a loose sliding fit into the wheel shroud extension , it should expand into the shroud diameter for a sealed fit once the engine starts up.  . Once I have the mounting ring mounted to the gearbox and determine the wheels position within the shroud I can make up some sort of holding/positioning mechanism for the NGV . The 3rd stage wheel shroud on the "front" of the NGV will be left in place to be part of a slip joint for the interstage duct from the gas producer . Cheers John |
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Deleted
Joined: January 1970
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Post by Deleted on Jul 26, 2018 1:33:08 GMT -5
Hi John
Very impressive work, holding that peace of stainless with it's thinish wall section, would of not been ease on any lath, nice work, looking good
I guess the solenoid had been braking down for a bit, and the other improvements will have helped, extra 1,000 is a good improvement
Chat Soon
All The Best Andy
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Post by racket on Jul 26, 2018 4:27:46 GMT -5
Hi Andy
LOL, after that stainless tube popped out of the chuck for the upteenth time whilst only being able to lightly clamp it internally to prevent distortion , I just had to find a way of holding it so that I could machine a true round surface , shrinking it onto the bespoke backplate that was running true in the chuck provided the answer , initially I was also going to tack weld it as well , but after doing a couple cuts it felt solid enough to continue.
Because I couldn't run my lathe slow enough for such a big diameter there was lotsa squealing despite only being able to do very shallow cuts , it was a long slow job spread over several hours to get that bit of pipe into the shape I wanted.
The whole assembly weighs quite a bit unfortunately , that NGV is a weighty piece of gear , theres a lotta metal in it .
Hopefully by this time next week I'll have the "spider" made and I'll be able to get an idea of how it all looks mounted on the gearbox .
Slowly slowly , it'll come together :-)
Yeh , the extra RPM will be a help , even though its only a bit over 1,000 rpm extra , when we workout the difference in tip speed squared , it requires another 20% more power , so a good improvement
Cheers
John
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Post by racket on Jul 28, 2018 21:38:16 GMT -5
Hi Guys The legs are on the "spider" Tack welding in place , square to the central tunnel, I made up a crude jig to bolt the tunnel concentric to the plate .  Just a case of slipping the leg through its slot in the tunnel to the correct depth then clamp it to the jig plate  I left ~1 mm projecting inside  All welded up  Next job is to fit it to the turning jig in the lathe and machine a step on the outer extremity of each leg that will allow the outer ring/wheel shroud to be fitted concentrically Cheers John |
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Post by azwood on Jul 28, 2018 22:35:02 GMT -5
Nice job your doing there with i had a lath its on my list
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