Later, later, later Just got a call saying my nitric acid is on its way in what they called a ''high security van''...hmmmmm cant wait to see the neighbours faces when that pulls up...
Thanks, I kinda forget about it sometimes, its part of the furniture now Made a start on the oil pump bracket pattern, Ill try not bombard the place with pictures of timber, but the few shots that are in at the start are there to show the angles necessary so that it will withdraw ok from the sand, the draft angle is 5 degrees, it works for me, This is where I chose to put it in the end, Cant be too hard... Turning some bits on the lathe, these will be the bracket mounts/stands, Like so, Cutting the ribs, again, 5 degrees on each side, And finished, Again, 5 degrees needs to be cut on the ends to match the 5 degree angle on the turned 'stands', And they also need to have a radius scribed on the end at that 5 degrees to fit snug, this seems like a lot of trouble, but in the end they'll bond better, and take less filling, plus, Cabinetmaking is what Ive been doing for a long time, so this is quick and easy when your used of it, And glued up, Im using superglue, not very 'pro' but its fast, And now glued lightly to the pump to make it easy build up, I allowed a bit for shrink on all three pads, you can see its a bit past the spot face on the pump, 7mm for the flat parts, And the spine onto front of rib, My parting line will fall where the walnut meets the yellow pine parts, its not all on the same plane so Ill have to mould down to it, you'll see what I mean later, Still a good few ribs to go in to strengthen, but the backbone has been laid out, Ill also be putting a 'lid' on the rib up-to top bolt and it will meet the pad nearest the outlet side of pump, Once that's in I can add the last pad at the timing belt end and brace with ribs from the middle pad, its far from finished, but its pretty handy and I hope to get it wiped tomorrow eve so I can transform it into alloy. I want it as strong as I can where it needs to be, but at the same time as light as I can. Brian.
Shrinkage I like. I worked, for a few months, in the Pattern Shop, at Laycocks. All they could talk about was: "Shrinkage"! Very, very, difficult subject. Hope to hear more soon Brian.
Aye, the aul shrink rule. Dimensional shrink is dare I say, calculateable(did I just invent a new word?) But its the heavy cross-section shrink thats the killer, itll actually suck out the thin areas as it cools to feed itself, or not, and end up sagged...chills and good stout risers over the 'fat' bits cut down that though, keep them *****es fed
We have mould flow for plastics in the CAD package here, not sure if we have anything for metals. Casting is a black art though. When working on 65` powerboats 2 hulls from the same mould could be 6" different in places, nasty horrible GRP, plenty of fettling going on there. And it was feet and inches when i worked there, with drawings mostly at 1:32 scale, messed up my measurements a number of times being a post decimalisation bloke meself.
Ha! the advantage of being my age is: School and college = Imperial (slugs, poundals, pounds-feet) University = Metric (beautiful Newtons) Our lecturers struggled, more than we students, with the change over! Mind you they were very old, I bet some were in their 30s! Actually our Prof was about 90, and he picked it up quicker than most!
I dont know would it be any use either, I have access to one here too if I need it. I find practice good, playing around with gates, chills, runners, gates, etc, even casting flat thin objects with a ball on the end to see how they act....cold fronts meeting is the biggest factor on multiple gates but you can get them too meet in non stressed areas like you would with injection moulding, or even get them to meet outside the mould cavity...but you know all that lark.
Got the pattern almost done, Ill let the pics do the talking as they're pretty self explanatory, Glued, Fitting the pulley backwards made it easy to stand on end and swivel-able, Same sliver underneath, I had to but in the small little wedge piece after to give me the draft angle I needed there, More ribs added also In different places, Onto the last pad, With the pulley the right way again you can see how it lines, I want it as close as I can, If I have to machine end pad to clear I will, but I wont have to too much, Off and flipped over to fit the curved ribs, space is very tight here on one bottom rib so Ill be feathered in half way as below, A half hr tomorrow will finish this out, then Ill sand the draft angles on all the pad(s) perimeter as its currently a 90 degree edge, once thats done Ill clay up any spots that need blending and also fillet all sharp meeting points with clay also(modelling clay). After that its onto moulding it up and pouring, I hope to have the finished part in my hand by the end of the evening. Brian.
Wot glue do you use Brian? Cow Hoof or Gorilla Seamen? EDIT: Just realised you state super-glue, a few posts below. And, I can now see a bottle on your last post! Would yous believe I could be such an ejt with Mayo genes?
Speaking of glue, that gorilla glue is deadly sometimes, it foams as it dries and pushes things apart if there not clamped, the first time I used it I didn't bother clamping and in the morning all the door joints had pushed open 3mm, leading to 5 binned doors[:^(] Got the draft angles sanded in on the top pads, gave the lot a mist with water to raise fibres and went over it with some 320 paper when dry, started claying in the fillets then with modelling clay(Pottery stuff). I found the clay works better if the pattern is damp as it doesn't suck the moisture out as fast and stays workable for longer. Small fillet knives, a 5mm ball on wire, and fingers were the way ahead here, finished up with a damp brush to smooth any corners. This clay is to be kiln fired, but it air dries pretty hard too so it should be ok. Ill run over it with sand paper once hard to get things perfect if it needs it, then a coat of sealer and mould her up. The clay, And the pattern as it sits now, Brian.
I like to look at Brian G's wood! Good to see you have survived the "Nitric Acid Experience" this weekend too. That makes the "Jimmy Hendrix Experience" look like a bunch of lightweights.
[Rolf Harris] Can you guess what it is yet? [/Rolf Harris] What gets me is that you make it all seem so simple, usualy people manage to make things like this seem so much more complicated and advance than it actualy is, but you make it seem like anybody could do it, top work! PS Once you make the mould, you HAVE to sign it with a dremel or something, so the end casting has your own name on it. Great way to prove any "Doubters" wrong
I sure did Its not 'as' bad as I thought, it does fume when you open it, and is scary in general, but I did a few tests with it in its 70% state and Im ok with it now. You do have to watch of course what it contacts, and the different fumes it gives off when it comes in contact with differnt things but thats chemistry for ya Here it is, looks pretty 'safe and innocent' In its container doesn't it!
Just spotted that bit you snipped there earlier, I hoped no-one would point it out Thats the thing with stuff, almost all stuff is simple if you break it down, and explain so as you go, the most thing you need is patience, which I have, lots of. If your the type that gets stressed easy then walk away, you wont stand a chance, but it is really basic, using basic tools, and basic materials, but in different ways, or more optimum ways should I say. Anyone could do this, its not hard, and requires no special gear, just your two hands and a quiet workshop. I dont think anything is Impossible really, if you break it down and think about it a bit. Anyone who tells you different is just trying to make a big deal out of what they are doing, I like to just plod along...dealing with dilemmas as I go As for my name, It did spring to mind alright, I may just do that anymore, I could make a wire letter stamp and just stamp the sand before I close the moulds.
Been there, done that! I have made my doors by laminating two planks of pitch pine back-to-back. Put the planks together with Gorilla. Put my sons weight lifting weights on. In the morning, the whole top layer had floated sideways by about 50mm!
