L-Plate Rider
Frits, As I am a mechanical engineer instead of a physicist, I normally refer to Celsius instead of Fahrenheit. I forgot for a moment about the different conventions around the globe.
The PLA starts melting at 150 to 160 degrees so raising the temperature to 500 degrees Celsius was mainly to fully dry the shell.
Hardcore Biker
[QUOTE=Peiter;1130908250]Smoothing the PLA print is indeed still an issue I'm adressing, as the surface was quite rough in the final aluminium cast part. I have tried a chemical on the PLA but I didn't like it as it softened the part and with epoxy I'm affraid it won't burnout correctly. On the next iteration of my cilinder, I'm going to sandblast the parts softly with glass beads to smoothen the side surfaces of the print.
QUOTE]
Peiter, when we bought our Dutch made printer (a Leapfrog Creatr with twin heads) one of the features was that one could print with ABS and use PLA for the supports, this being dissolvable in warm water. Unfortunately this didn't seem to work very well, maybe we just got some crap filament. Seemed to be a nice elegant way to go, printing a lost PLA part especially with a fairly low density infill, say 20%, this would allow the water to penetrate fairly easily. The little experience we have with the "set" investment is that it is like concrete and that not really affected by water, but would certainly need drying out. Other options being HIPS and PVA.
Still, if you have had no real difficulties with melting out, then we might give it another go.
Especially as this Ryger thing is getting simpler by the day....................Frits.
Thanks
"Success is the ability to go from one failure to another with no loss of enthusiasm.”
L-Plate Rider
Hi Ken,
I have never heared that PLA is dissolvable in water, the only (printable) material I know of is PVA.
All my printed cylinders were at around 20 - 25% infill such that it was quite easy to melt away.
As I think I mentioned earlier, I printed the cylinder in sections to avoid support material and glued them together afterwards to form the complete cylinder.
I'll try to make pictures of the cylinder section tonight, that will make it better understandable.
Below is the first version where we suspect that the foundry didn't have to mold upside down long enough such that still some PLA was trapped inside:
The second version, where I also corrected some mistakes in wall thicknesses and stuff was already much nicer:
After some Dremel love and glass bead blasting this turned out perfectly fine in my opinion:
Regarding the Ryger, I am reading everything on team ese .. with interest and I've heared some rumours here in the Netherlands too.
At first I thought, what the heck, just throw this cylinder away and wait for more information such that I can start making something similar.
However, after some thought, I considered I should first finish this piece and gain experience in every part of the process.
When eventually enough information is available I can still go that route and atleast I then know all the potential problems of casting and machining a cylinderkit
Cheers,
Peter
Forum whore
Keep up the good work, Peiter. I am a physicist who likes to get his hands dirty every now and thenOriginally Posted by Peiter
.
L-Plate Rider
Polinzei
Interesting item, I have been down this route casting ports for a water cooled 125 BSA Bantam racer in steel. When you get to the casting consider the removal of the vitreous coating inside the ports. These have to be removed with shot blasting so you may need special 'tools' to allow you to get into the smaller passages. If you are water cooling the passages may be difficult to get into and clear with an obvious risk of poor cooling.
Muddler/Dabbler.
To me, this forum is good in that even people like myself who only play around with different processes, can get help and get to talk to people with up to date information on various processes which even as recently as 15 years ago was not universally available!Keep up the good work, Peiter. I am a physicist who likes to get his hands dirty every now and then
We already have a resident 'wizard' in traditional casting and patternmaking here on the forum (not me, I'm only a peasant boy who just wants to know). He is well versed in and has successfully designed and built a lot of stuff,
He keeps me and others on the right track with our endeavours and no doubt is extremely interested in the work that all you overseas engineers/ physicists/and experimenters (of all kinds) are doing as well - long may it all continue!
Back to bed now - just got up for a drink of water!
And yes, I talk too much!
Muddler/Dabbler.
They are still racing Bantams in the UK? - do they still use the 3 speed box?
Takes me back! I once did up a Bantam for racing (George Todd head and all that) and enjoyed it very much - a water cooled Bantam was my ultimate goal at one stage, (inspired by the Greeves Silverstone), unfortunately that all disappeared when the Suzuki T20 came out!
L-Plate Rider
We race under the British Historic Racing umberella and yes it is still only a three speed gearbox. Perhaps a bit faster then the Todd head days but still just as much fun.
still basking in the glory..
www.bsabantamracing.com and a face book site..
L-Plate Rider
Hi, I have been down this route casting steel ports for a water cooled BSA 125 Bantam racer. If I may, could I say that it is worth considering the post casting issues of removing the ceramic from within the casting. We had a problem with small passages getting the shot blasting nozzle into the holes, it needs 'special tools' making to achieve clear passages especially if they are water cooling routes.Polinzei, cool looking stuff!
Below is my first part on the PLA made cylinder and casting it;
At first I wanted to buy a cylinder kit made by Stage6 or a Malossi speed 7T which all perform reasonably well.
However, in december 2014 I stumbled upon a guy on google who was casting an aluminium piece directly from his PLA printed 3D model (http://3dtopo.com/lostPLA/).
This made me interested in the subject and together with a metal foundry nearby where I live, we tried a sample ourselfs. It turned out that PLA will melt away 100%
without residues, so the method was indeed quite good to cast cylinders!
Together with a good friend we then formed the idea to start designing a cylinder ourself where we could work around the following:
- The original stud size is 56x56 with 7mm studs, this pattern is too small for a 47.6 bore cylinder to shape it correctly at the exhaust and b-port.
- Most aftermarket cylinders have the exhaust channel at a straight angle whereas we have tried to obtain the desired 20-25 degrees (if I recall it correctly).
- Cooling of most cylinders for a Derbi engine is asymmetric on one side of the exhaust channel.
First, I started making silicone molds of all sorts of cylinders I could get my hands on, a friend's 22 hp 50cc, an Aprilia RSA, a Honda 2007 a-kit, a KTM 125, etc..
(in the picture below are only a few of the silicones, I have enough to fill my desk
Attachment 316263
With these molds, I went to a Fablab where they had a reasonable 3D scanner and I scanned the molds with an accuracy of (If I recall it correctly..) 0.1 mm.
Next, I sat together with my friend and given our appetite and enthusiasm to discover things ourselfs (in some people's eyes stubbornness), we decided to go with the Honda port lay-out as shown in the images.
Attachment 316260Attachment 316261Attachment 316262
The Honda cylinder had the A-port its edge nearest to the B-port almost perpendicular to the bore and aimed at the other side. We decided to go with a more common direction of aiming the A-port further towards the C.
The axial angles are set to about 22 deg. for the A-port, 8 deg. for the B port and 50 deg. for the C-port.
After designing the cylinder in CAD, it was time to print it in PLA. As we had to remove / clean the white shell after casting, we decided to remove the "roof" above the exhaust port such that we could thoroughly clean the cylinder.
Attachment 316265
Inherent to the FDM process used by our Ultimaker 2, overhangs and roofs larger than 50 or 60 degrees require support material to deposite the material during printing. Therefore, we had to design the cylinder in such a way that it was printable and all the support material was removable.
I'll elaborate on making the design printable and the actual casting next time, hopefully you guys like it!
cheers,
Peter
regards,
Roger (125techdir)
Muddler/Dabbler.
Breezy, thanks for the links to the gearbox drawings etc. unfortunately they would have been much more useful to me over 50 years ago when I was struggling with a (so called) "close ratio" box which had a super high 1st gear and a second which was just slightly lower than top! (came in handy when there was a head wind of course).
L-Plate Rider
Wood everywhere - Love this method. (My 135cc piston block pattern)
Muddler/Dabbler.
You have plenty of wood in Indonesia, so it's a good idea to make good use of it. (while it's still there).
Have you made any moulds or poured aluminium yet? - I think that's a lot of fun too, even if I have about 50% failure rate (I don't talk too much about that of course!). - all going well, so keep it going.
Forum whore
Wood, yes cheap (free) and available, unlike money, It does grow on trees.
The Ryger style cylinder has been slow lately (work keeps getting in the way) but here is one of the water cores ( less the core prints ). I will be making a core box from this shape.
Also fitted the charging coils and fly wheel to the sleeve engine. I've decided I'm going to just get the sleeve engine running without the gearbox for the moment. A bit of a wast of time but but I just want to hear it run (or not). Also have several other cylinders lined up to test on this bottom end, one being a bastardisation of Frit's FOS. I'm glad I waited to finish the FOS as now there will some changes I've learn't from the Ryger saga.
By the way, if anyone out there has a YZ250 engine (and or gaerbox) for sale I'm interested. I think 2002 to 2007 model? This gearbox will be fitted to the sleeve engine.
L-Plate Rider
Yes, I've made the crankcase, no gearbox. Piston block is unfinished, I still improve its pattern.
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