51 replies to this topic

[1977 Loud_Mini]

regarding SolidWorks, the G and M codes etc will be generated as i've been shown by opening the drawn 3D part into AutoCAD from SolidWorks and then going through the specific operations to extract the Codes for the work required. I may be interested in the alloy but i'll have to do some more researching yet. Any idea on prices? After all it took around 6 hours to draw the piston. Half of which was drawing one not to any dimensions to see if i could get the basics of it drawn.
With the rings i have read that people who want exact ring tolerances actually buy oversized rings and adjust the end gap to their required specs for that engine?

[1977 Loud_Mini]

15 thou is about what my 73.5 powermax's were, only measured with a vernier though so not terribly accurate.

Thats what i'd be using as a kind of template for rough measurements as i have 4 here not really any good now.

[Shifty]

For rings, try this place..

http://www.fwthornton.co.uk/

[1977 Loud_Mini]

For rings, try this place..

http://www.fwthornton.co.uk/

Thanks for that, would be a great help to match rings to my pistons.
I was thinking of going 1.5mm thick top ring, 1.5mm second ring and the oil ring as 3mm does this sound slightly too thick with the friction and everything?

[1977 Loud_Mini]

Just going back to extracting the G codes, it was SolidCAM 2009 that was used and not AutoCAD (that was me getting confused with different software used in another lesson).

[MRA]

I use ONE CNC Mill pro with 4th axis for the mill
and Lathe pro with driven tooling for one of our lathes

Used bobcad.... apsolutely rubbish siftware and rubbish company.... no support what so ever...

[Rabtmac]

Saw this post and had to stick my oar in hope you don't mind.
I used to be a foundry Foreman for many years and we cast in sand,hand dye casting and pressure casting
Casting a piston if you could find the right material would be tricky to say the least
No matter how hard you try to degas the alloy before casting you will always find inclusions in the final casting that once under pressure will cause problems.
We played with the idea of installing a new "squeeze casting" Machine but the cost was a little on the high side at around half a million (and this was over 10yrs ago)
It works on a process of heating the alloy in billets of whatever size you need but heating them up till they are in the state between molten and solid.
This billet is then taken by robotic arm and inserted into the casting machine and "squeezed" into the shape you want
This leaves almost no inclusions and is perfect for the production of aircraft parts and high end automotive parts.
This is the only way I would ever consider making a set of pistons to fit in any car and if you look at the costs this would generate
Do yourself a favour buy a new block and pistons and make some just as a project for college.
Got a feeling if you put any you make into a block your going to be disappointed and your bank account is about to suffer.
Sorry if this was a bit long winded.

Edited by Rabtmac, 25 January 2011 - 11:18 PM.

[Mini Adam]

I was thinking to get some 74mm piston rings and then file them down to the correct ring gap so that they will be sort of custom rings for my application.

This doesn't sound particularly accurate to me? :/

[MRA]

I was thinking to get some 74mm piston rings and then file them down to the correct ring gap so that they will be sort of custom rings for my application.

This doesn't sound particularly accurate to me? :/

That's because it isn't....

[Stevee]

i made a piston at college just for an Air Engine haha xD just a round bit of ally to run up and down a brass cylninder

[mini93]

theres companys out there who will make a set of pistons for you... but unless your doing a run of them they certainly still wont be cheap, plus then finding correct rings would be a pain, would have to go to a ring manufacturer and give them dimensions and see if theres an OE ones to suit

[Dan]

This is the only way I would ever consider making a set of pistons to fit in any car

Didn't Hepolite try squeeze casting and give up on it after only a few years though, going back to regular casting for the bulk of their pistons?

[100ev8]

buy a cheapy cheap 998 runner of ebay , make 1 piston and off you go . be good to see what happens

[Rabtmac]

This is the only way I would ever consider making a set of pistons to fit in any car

Didn't Hepolite try squeeze casting and give up on it after only a few years though, going back to regular casting for the bulk of their pistons?

Not sure about that but I remember going to the manufacturers in Germany and talking with the guys that had come up with this process and even they suggested it only be used for long runs or if the parts needed had to be near totally inclusion free (aircraft suspension etc)
We ended up sticking with the Freck injection moulders (standard 500ton pressure between the plates) and had a couple converted to 1500tom plate pressure.
They did us fine and will last forever
(original machines were already 50yrs old before conversion) there built like tanks and just keep going.

[Big_Adam]

buy a cheapy cheap 998 runner of ebay , make 1 piston and off you go . be good to see what happens

I'm with this guy, be a pioneer of engine whatsits.