Focusing on our workshop that specialises in repairs and restorations to BSA Bantam motorcycles as well as other motorcycles. We also manufacture a lot of our own parts and this channel details how we accomplish this.
Hey Tony. Looks like you had a better outcome this time around. It's a shame the sand you're currently using is a little bit too coarse ?? I was originally thinking it might add to the texture of the surface. But it came out a little bit rougher than I thought. Looking forward to seeing the end product 👍
Yep I hear ya.........I was given some good sand from friend and purchased sand from a hobby foundry supplier that was as coarse as driveway gravel. It is terrible, hence you saw the surface finish. I couldn't get the radius to work the way I wanted in the CAD program, so I had every intention of rounding surfaces off a bit more. Therefore I decided to use my crap sand. If I could have got the pattern profile exactly the way i wanted and I had fine sand I think I would have left it that way as it came from the mold..........Thanks for watching
I don't have a CNC router to do the foam and my mate who does is away. So I thought I'd do the sand casting. I haven't finished with the lost foam just yet!
Yep you're right.........I have started machining them, and I've been videoing it as well. So you'll get to see the finished product in the next video.
Thanks mate, I have just become possessed of a a beaut little D1 which is in half a dozen boxes so your videos are a real treat, I am also an aircraft engineer coming up on 50 years in the business so I get your procedural approach to rebuilding engines.
Pack the pattern like green sand with the fins down, make a ring-shaped access gate with four others Connecting to a single central one, place a vacuum cleaner to form a vacuum - ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Iz6MmiG2o7k.htmlsi=A374JbwfBpsfBK56
You need multiple gates to speed up arrival at all points, you still have to use a vacuum system that you can use your vacuum cleaner, only then will you be successful with so many fins.
Você precisa de portões múltiplos para acelerar a chegada em todos os pontos,ainda tem de ultilizar um sistema de vácuo que poderá usar o seu aspirador de pó só assim obterá êxito com tantas barbatanas profundas veja os meus vídeos passei pelo mesmo calvario
For casting in foam made with thin pads such as barbatanas, the aid of a vacuum system. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nSyXeEqx22c.htmlsi=O2-aN_CiiZPdxvd-
Some ideas experimental- Just having a look at the finished product seems pretty decent bar the extremes of the thinner sections. The fins not filling out - maybe air is getting super heated and trapped long enough to stop the AL flowing into the extremity of fins . I'd try gluing a small cylinder/square poly tube that runs across the highest parts of the fins ( as it laid in bucket) and extend that to egress air at top of bucket. You will have to grind off that if flows to that extreme. The other possibility is running a higher bucket and increasing the pour height for more liquid pressure into the cavities.
Very close. Not sure what alloy you are using but I suspect 50-75F higher pour temp would have yielded a complete casting. Fins can be tough because they are designed to transfer heat and they do.....to the mold too. I wouldn't go out of your way to make the sprue round. -Probably better off square. I'd probably tilt the head slightly fins down and branch the sprue where it contacts the head to distribute the hot metal. If so the previous pour temp might get you there. Best, Kelly
Thanks Kelly......I agree with the pour temp, it could have been a bit hotter. I'm having another set of foam heads machined so hope to get a pour in soon. A branched sprue is a must to get the metal to the extremities.........But I'm getting closer!
Kelly Coffield definitely has that knack for making it look easy. It's a shame the pour didn't turn out as planned. But, it's all part of the learning curve. Machining it out of Billet as someone mentioned, wouldn't have that original factory look that would spoil the whole build. I'm sure you will have a great 2 months away. The good thing about a long holiday, home looks so much better when you finally come back to it 👍👍
Larger ID sprue, e.g. 25+ mm - with three or more connections at the very bottom, and three “bleeder” vents at the top?? Also, you want to feed into the thickest part of the casting, with a big reservoir of molten metal to feed the casting as the metal filling the pattern shrinks. Not done *lost foam* in Alumin(i)um, but have done a lot of green sand in it. My brass hammer head was lost foam, done in a college foundry over thirty years ago. Finally, go about 10 degrees warmer. Fins can be tricky - and I have done finned castings.
You might try casting with the head flat in the upright position with as long a feeder as possible and feed thru what will be the spark plug location. The heavier base could keep heat flowing up in the fines to give the fill a longer time before freezing off.
Adjust the height of your fins when cutting the foam head.. it looks like you just need a little bit more space to make way for the foam that gets trapped and turns into carbon
You are getting close on the head casting 2 things crossed my mind when looking at it, either the alloy is cooling to quickly or the gasses from the foam aren't escaping quickly enough and there is a bit of a gas pocket. Perhaps using a slightly larger feed sprew diameter in combination with your twin gates might help as the larger volume of metal won't cool as quickly. In traditional sand casting you use risers to vent of any gas out of the mold I'm not sure how it would work with lost foam but it may be worth some consideration.
Hi Frank.........You can't use a vent in lost foam as you'd have vaporising gases spewing back out on fire. But I think you're right on the money with temperature at the fins. I'm going to reduce the pattern volume as the base is thicker than the original and split the entry gates. The position of these will be a critical factor as well. Sprue size may be increased however I am now running close to the capacity of the crucible. I'll keep trying and thanks for commenting.
Hi have you though of puting a vent on eather side of the outer fin to alow anay traped gasses to flow out of the mold ?? but its gettinh brtter every tme will also have a look round for carb bits and bobs for you .
Hi.....The trapped gasses are getting out. I think the issues is getting enough metal into the mold quickly before the metal is cooling. carbies have been organised as I'll fit up Mikuni's.........Thanks for the offer and commenting.
It was pretty big to start with.........I think the single point entry into the mold was the issue. I'll split the sprue into 2 and have 2 entry gates next time.
As a retired Engineer with little foundry knowledge let alone experience, this is great to watch, to see how Bones deals with the process problems step by step. Have a great time on holiday. If you are anywhere near Leighton Buzzard pop in for a cuppa.
like the casting, yep its a bit hard to make it work but then if its easy then anyone could do it! Don't get with putting metric screws in imperial inch machine? Got a Herbet 2D turret lathe here to set up for a job no one with a CNC wonted to do. Have fun LOL.
Thanks........Not sure about what you mean with putting metric screws into imperial machines?? Like you people often ask why I don't get parts CNC machined. It's because I can't justify putting an order in for 2000 items. I can punch a couple of hundred in a day and that's all I need.
Hello my friend. You are getting closer each time with the casting. I know nothing of casting but fully appreciate and support your attempts to get it right. Thank you so much for the mention, never expected it! Have a great time in the UK!
Hi Mate..........was saying to Dean I think I'm close. Just need to turn the brain off and enjoy the holiday. I'm bringing friends over to the UK who haven't been there before and I'm looking forward to having a look at the continent. take care and get that turbine done!
Great video mate. Awesome to see the third generation is out in the shed working on super cool bikes . Kee0 up the fantastic work greatwork on the casting
Hi Tony, I am replacing the gear shaft on my D3 engine (damaged splines) and want to take the claw off the old shaft. Am I correct in thinking that the claw assembly needs to be tapped down the shaft to gain access to the top retaining wire clip, before it can be removed from the top of the shaft? I have given the claw a few exploratory taps with a hammer using a socket slightly larger than the shaft but the claw hasn't moved and I didn't want to do any damage. Would some localised heat help? Thanks Joe
Hi, without seeing what you're dealing with makes it a bit difficult, but you're on the right track. The selector claw does have to be moved down the shaft to expose the retaining clip so it can be removed. I'd be more inclined to try penetrating oil (50/50 acetone and Auto transmission fluid is the best) for a while and then keep going as you have been. If you were going the heat option I'd change out the selector spring.........In fact I'd change out the selector spring anyway. The selector springs currently being supplied are bent wrong. If you change this out pay close attention to the selector claw position in relation to the gear change selector plate. The selector plate should sit dead centrally between the selector claws. If it doesn't the selector spring will have to have the bent leg bent up, so the selector spring will make the selector claw sit centrally...............Hope this helps.
@@OzBSABantams Thanks Tony, good to know I'm on the right track. Have applied penetrating oil and will let that soak into the splines before having another go. I will definitely be replacing the selector spring and keep and eye out for the differences in spring bend and how that effects the claw position in relation to the selector plate. Thanks for tips. Best wishes Joe
