Team GPR

**Sketchy_Racer** · 6th August 2014, 22:42

Originally Posted by seymour14

SolidWorks/SolidCam.

Have had experience with Rhino, Powermill and MasterCam, but this is the one freely available to me, and I must admit that it is quite user friendly (considering I am self taught). Each had their own quirks, but like anything, it comes down to being precise with your setups and thinking threw your designs and mill strategies.

Finding enough time to finish when you are getting on a roll is another conversation entirely!

Cool, I used solidcam for a little bit but work used Esprit and I had HSMXpress at home for 2D stuff. HSMXpress integrated into SW much better than the others I found but was a little more limited in toolpath generation.

Longest program I nutted out was a injection mould insert that needed 3D milling on the 4th axis. Took a couple days to get it to all work!!

Once the cylinder is completed are you going to weld the insert in to cover over the transfer ports then get it plated or are you going to sleeve it with cast iron?

**seymour14** · 7th August 2014, 08:21

Originally Posted by Sketchy_Racer

Cool, I used solidcam for a little bit but work used Esprit and I had HSMXpress at home for 2D stuff. HSMXpress integrated into SW much better than the others I found but was a little more limited in toolpath generation.

Longest program I nutted out was a injection mould insert that needed 3D milling on the 4th axis. Took a couple days to get it to all work!!

Once the cylinder is completed are you going to weld the insert in to cover over the transfer ports then get it plated or are you going to sleeve it with cast iron?

Looking at a Nicasil lined sleeve, press fitted in with a top hat arrangement, and may put a little extra "bump" on the top hat to act as a location means. The plating will come at the end and I will see if they can line the ports with it as well, no real benefit, but it makes it all similar throughout with a "skin". Depends whether the process allows for it or not.

**F5 Dave** · 7th August 2014, 10:15

I'm just closing my eyes wishing I could do something like that. Makes my 1978 MB look like an axe.

**seymour14** · 7th August 2014, 10:34

Originally Posted by F5 Dave

I'm just closing my eyes wishing I could do something like that. Makes my 1978 MB look like an axe.

Don't worry Dave, I'm not going to talk this up. Interesting project and I will give it my best, but it is very much a prototype, the day it comes to fruition we will all be standing around the Dyno with bated breath.

May become a very pretty door stop....

**F5 Dave** · 7th August 2014, 12:14

my concern would be the differing expansion rates but with the sleeve it should be sweet. I can't see it being anything other than a little bit awesome or better.

**Grumph** · 7th August 2014, 13:01

Originally Posted by seymour14

Looking at a Nicasil lined sleeve, press fitted in with a top hat arrangement, and may put a little extra "bump" on the top hat to act as a location means. The plating will come at the end and I will see if they can line the ports with it as well, no real benefit, but it makes it all similar throughout with a "skin". Depends whether the process allows for it or not.

Judging by the relatively few nicasil cylinders I've dealt with, it doesn't "throw" very far. About 1.5mm into ports in my experience.
This leaves an edge which should be stoned for the good of your rings...
I'd imagine that to nicasil coat transfer ports, shaped anodes would be needed - and expensive.

**seymour14** · 7th August 2014, 17:53

Originally Posted by Grumph

Judging by the relatively few nicasil cylinders I've dealt with, it doesn't "throw" very far. About 1.5mm into ports in my experience.
This leaves an edge which should be stoned for the good of your rings...
I'd imagine that to nicasil coat transfer ports, shaped anodes would be needed - and expensive.

That is good to know, very little practical literature on the net on the subject. Can't go to extra expenditure for a Bucket!

**Sketchy_Racer** · 7th August 2014, 18:54

Thinking about the thermal paths, I recon that it would be vital to have as much of the cylinder as 1 piece. Thermal overload will be the HP killer here if you can't get the heat out it will be game over.

Keeping in mind that it is fairly well proven now by the ESE guys that it's a tough job to reliably shed anymore that about 28whp worth of heat.

What's the plan with fins? Going to machine them into the cylinder as it sits?

**seymour14** · 7th August 2014, 19:08

Originally Posted by Sketchy_Racer

Thinking about the thermal paths, I recon that it would be vital to have as much of the cylinder as 1 piece. Thermal overload will be the HP killer here if you can't get the heat out it will be game over.

Keeping in mind that it is fairly well proven now by the ESE guys that it's a tough job to reliably shed anymore that about 28whp worth of heat.

What's the plan with fins? Going to machine them into the cylinder as it sits?

Regan has been making scoops for the bike which should help. The top third of the cylinder will be scalloped out, like a flower pattern as it comes out and around the studs. I am going to do some trick stuff there as well, but it will be a case of a picture says a thousand words, so will post pictures once done. Finnage will be as much as is practical, and I am trying a new concept here as well, again pictures will be necessary. Needless to say, the fins will be welded on after, and will need to suit the confines of the GPR frame.

Shall try to do a little bit more each week, but this is the "go" season at the moment, time is at a premium.

**seymour14** · 10th August 2014, 19:23

Great show, we did our bit. Played clips of the racing and got a good response.

Images from the show.

**seymour14** · 12th August 2014, 20:57

Fins coming together. Deep grooves machined in barrel to aid cooling (the curved face you can see on top is machined in two more times at 10mm intervals below), fins will snap fit into the shallow portion, get welded, anticipating at least 6 differently machined fins to be put on. Exhaust port means a little bit of shaping required for some of the fins.

Hopefully pictures are a bit more self explanatory.

**Farmaken** · 13th August 2014, 07:30

Dang, she sure is purdy ....

**seymour14** · 15th August 2014, 18:33

Originally Posted by Farmaken

Dang, she sure is purdy ....

Just for that, I have given it a makeover...

Latest developments are 6 fins, these will snap fit into grooves machined around the barrel for good engagement. Then welded down the fins seam, or welded to the exhaust port, depending on their placement. The two "whole" fins will have a bandsawed slit put in them to get them into place.

My rather unique design has a third more surface area on the top. Hot air rises! It may even help break up the airflow directed onto the head via the several air scoops. Either way I do not expect they will provide more then a couple of percent extra cooling aid, but it will be interesting to take measurements from these fins once in action. The largest fins are 200mm square, very similar to a 250cc or 400cc CZ motocrosser for comparison.

She will be distinct, that much is a given.

Some more machining required in the exhaust port, then it will be the all important sleeve. That will be a challenge indeed. Post pictures of the one I get right....

In the picture you will also notice the mandril I quickly knocked together for holding the barrel in a dividing head as I machine the rest of the grooves that go from the exhaust port round to the opposite side. This is for the four lower fins, I want good engagement.

**Grumph** · 16th August 2014, 09:19

Good engagement....there are several high temp epoxy fillers which are metal based so have good thermal conductivity properties. A fillet in epoxy may help....
Some years back a customer who made light fittings for a living was having problems holding thermocouples onto fittings for heat tests. I asked a mate at Air NZ workshops and got some very high temp Araldite which they use for gluing thermocouples onto jet combustion chambers. Can't remember the Araldite number sorry, but these things are about.