4stroker Posted February 13, 2008 Report Share Posted February 13, 2008 hey guys, ive got an rz motor that im dropping a 4mm stroker crank into. i dont wanna run a spacer under the barrels so im porting them to suit the stroker and gonna run a pro design head with my own design domes. (local machine shop has cnc lathes and milling machines, and ive got a hunk of 6061 aluminium ) what is the most accurate way to measure the raised dome of the piston, so that i can design the proper squish angle relative to the piston? are there any diagrams or anything floating around that show the radius and height of the dome? im using 66mm wiseco 795 pistons, so when maching the 2mm step into the domes, im going to make it exactly 66mm as well. am i going to have to increase that diameter when i go to the next oversize piston? (ill prolly have to make new domes anyway when that happens, as ill have to use blaster pistons for the next oversize) any help would be greatly appreciated! thanks, mark Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 13, 2008 Report Share Posted February 13, 2008 hey guys, ive got an rz motor that im dropping a 4mm stroker crank into. i dont wanna run a spacer under the barrels so im porting them to suit the stroker and gonna run a pro design head with my own design domes. (local machine shop has cnc lathes and milling machines, and ive got a hunk of 6061 aluminium ) what is the most accurate way to measure the raised dome of the piston, so that i can design the proper squish angle relative to the piston? are there any diagrams or anything floating around that show the radius and height of the dome? im using 66mm wiseco 795 pistons, so when maching the 2mm step into the domes, im going to make it exactly 66mm as well. am i going to have to increase that diameter when i go to the next oversize piston? (ill prolly have to make new domes anyway when that happens, as ill have to use blaster pistons for the next oversize) any help would be greatly appreciated! thanks, mark You've got three choices for reverse engineering (using the engineering term loosely) the domes. 1.) Cut one in half and put it on an optical comparator. 2.) CMM machine. 3.) Make posite cast of the domes fire face and use traditional measing tools and/or an optical comparator. There are a few other really slutty options, but it sounds like you are trying to do a good job with this project. :thumbsup: Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted February 13, 2008 Report Share Posted February 13, 2008 There are a few other really slutty options, but it sounds like you are trying to do a good job with this project. :thumbsup: I'm always a fan for slutty projects Quote Link to comment Share on other sites More sharing options...
BansheeKid15 Posted February 13, 2008 Report Share Posted February 13, 2008 I'm always a fan for slutty projects I was just going to say i wanted to start using that term. (loosely also) haha. Sorry to hijack Quote Link to comment Share on other sites More sharing options...
4stroker Posted February 13, 2008 Author Report Share Posted February 13, 2008 You've got three choices for reverse engineering (using the engineering term loosely) the domes. 1.) Cut one in half and put it on an optical comparator. 2.) CMM machine. 3.) Make posite cast of the domes fire face and use traditional measing tools and/or an optical comparator. There are a few other really slutty options, but it sounds like you are trying to do a good job with this project. :thumbsup: thanks for the reply firehead, however i have no idea what your talking about lol... in what sort of workshop/lab would i find an optical comparator? and what exactly is a CMM machine? im gonna have to learn how to do this myself, or find someone to do it cheap, because i plan on keeping this motor for a long time so i will prob have to modify the domes every time i bore it... my grandfather used to work in the local foundry, maybe the pattern makers there could help me? or the guy with the cnc machinery, i hadnt thought of asking him for help measuring the piston... thanks again, mark Quote Link to comment Share on other sites More sharing options...
blowit Posted February 13, 2008 Report Share Posted February 13, 2008 thanks for the reply firehead, however i have no idea what your talking about lol... in what sort of workshop/lab would i find an optical comparator? and what exactly is a CMM machine? im gonna have to learn how to do this myself, or find someone to do it cheap, because i plan on keeping this motor for a long time so i will prob have to modify the domes every time i bore it... my grandfather used to work in the local foundry, maybe the pattern makers there could help me? or the guy with the cnc machinery, i hadnt thought of asking him for help measuring the piston... thanks again, mark I am not sure why you are trying to make your own when there are stroker domes available everywhere? Anyway, the machines Fire Chicken is referring to would commonly be found in many newer ISO certified machine shops and manufacturers. A CMM is a coordinate measuring machine used to accurately dim parts and compare part to model or drawing. I think casting is the easiest way out for you or simply use the slutty methods. They would work fine for this application. Brandon Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 13, 2008 Report Share Posted February 13, 2008 I am not sure why you are trying to make your own when there are stroker domes available everywhere? Anyway, the machines Fire Chicken is referring to would commonly be found in many newer ISO certified machine shops and manufacturers. A CMM is a coordinate measuring machine used to accurately dim parts and compare part to model or drawing. I think casting is the easiest way out for you or simply use the slutty methods. They would work fine for this application. Brandon Brandon answered most of your questions............ I think an optical comparator would be the easiest piece of pseudo percision measuring equipment to find. If you can't find one, you can make one by laying out a measured grid on a piece of butcher paper, hanging it level on a wall, then placing the part a precisely know distance from the wall, and finally putting a light source behind it. Once you get that done, you should be able to measure angles and disctances wit ha reasonable degree of accuracy (for what you are trying to do). :geek: Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted February 13, 2008 Report Share Posted February 13, 2008 heres an idea, run the pro design domes, but just machine them to accept the pistons. EASY! Quote Link to comment Share on other sites More sharing options...
yamaha04 Posted February 13, 2008 Report Share Posted February 13, 2008 PM DLnoss and get him to make you some domes. easy as that. they dont cost all that much Quote Link to comment Share on other sites More sharing options...
shanYE west Posted February 13, 2008 Report Share Posted February 13, 2008 PM DLnoss and get him to make you some domes. easy as that. they dont cost all that much Its probably not so much the cost.. but the shipping to AU. I imagine that wouldn't be cheap. But.. I've never shipped anything there so I'm just taking a guess. Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted February 13, 2008 Report Share Posted February 13, 2008 You could set it up on a mill and use a dial indicator to plot several points along the crown of the piston, just a thought. Quote Link to comment Share on other sites More sharing options...
4stroker Posted February 13, 2008 Author Report Share Posted February 13, 2008 all good ideas, thanks guys! im not making my own domes to save money, im making them myself so i know that they are set up exaxtly how i want them for my motor. eg i have very specific ideas on squish height, angle and band width, as well as a specific blending radius, not to mention a true hemispherical combustion chamber, which has to be a certain volume to get the compression ratio im aiming for... ive designed a set before for a friends 500cc TREX, but i just needed some ideas on the raised dome of the 795 piston, as the trex has a relatively flat top piston. ( i know how to design the dome to accept the piston, just needed an accurae way of measuring it) sure i could get noss or any other engine builder to make my domes, but why would i get all my specs together, send em off to them and get them to make it, when i can do it all here right in my own home town? also, believe me, it is alot easier to spend half an hour drawing my domes in autocad and having them spat out of a cnc lathe, than it is to modify some generic pro design or noss domes! thanks, mark Quote Link to comment Share on other sites More sharing options...
dlnoss Posted February 14, 2008 Report Share Posted February 14, 2008 Wiseco can provide you with the piston crown geometry, it may even be somewhere on their web site. TSR software is very helpful in designing combustion chambers if you or a friend has a copy. If not it is reasonably priced. -David Quote Link to comment Share on other sites More sharing options...
4stroker Posted February 14, 2008 Author Report Share Posted February 14, 2008 hey thanks for that man, i had a quick look on their website but couldnt find it, so ill try ringing them. thanks, mark Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 14, 2008 Report Share Posted February 14, 2008 You could set it up on a mill and use a dial indicator to plot several points along the crown of the piston, just a thought. That's a good idea if the mill a DRO on it. :thumbsup: Quote Link to comment Share on other sites More sharing options...
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