help with part holding..

[stirling lad]

I'm wondering if anyone can give me any tips on how to hold these things so i can machine them to the same size on the mill?
And I hope I've managed to figure out this resizing photo's caper!
...Mike...





 

[Lew_Merrick_PE]

Stirling Lad,

The parts appear to be some kind of shaft support.  My assumption from looking at the photos is that they span some base to which the gap at the base (i.e. the part sitting on the towel) somehow centers the support.  Further assumptions are: (1) that the "shaft" gets a clamp force applied through the bosses on one side of the (assumed) bearing support and (2) that the "faces" of the "bearing supports" are not all that accurately developed in the castings.

The first step that occurs to me is to locate off of the base using some kind of V-type clearance to lock the support frame to the "base" with some means of picking up the (assumed) index surface.  That would allow me to (A) face off the shaft support face and (B) bore the hole for the shaft with respect to the "base" and "index surface."  With that, I would complete the "clamp" that would allow me to locate and clamp the bore to a shaft and, using some kind of support to the side of the A-frame, machine the "base" to the shaft's position.

However, this is all based on an ASS-U-ME position...

[vtsteam]

Assuming they look relatively even, I'd probably use the webs of the uprights as a reference by clamping them down, onto a block on the milling table, and square off bottoms of the bases, first. That way I'd know the uprights would stand square instead of tilt.  If they weren't even, I'd shim until satisfied.

Then I'd start using the newly machined bases as my reference plane  to work the rest of the casting.

[vtsteam]

I'd use studs blocks and finger (toe?) and cross bar clamps to hold the castings to the block and table, to fully answer your question, since it was about how to clamp work and not necessarily how to align it.

[stirling lad]

thanks for your replies guys,,,
the A frames are from atop a Heinricci hot air engine..

My real problem,, the one i can't get around is this main casting block which is the water jacket and top half of
the displacer cylinder, needs a 2" thread cut underneath and a compatible thread cut on the brass ring photo'd
with it...I would then silver solder the rest of the cylinder onto the brass ring ...I have done all the other parts except
these two, (three counting the A frames).. .. the problem is its too big to turn on a mini lathe...and i'm usless at thread cutting as well...but i keep doing the lottery so maybe one day i'll be able to get a bigger lathe,, haha,,,

these photo's are old and most parts have already been done or machined close to finishing sizes...with a little help from
David Drillin...(well,, it is a hot air engine!! )


It looks like a really tricky thread to cut as there is very little room to do it,,length wise...well it looks difficult to me, but i have'nt really got a clue when it comes to thread cutting..

...Mike..

[vtsteam]

Not a very builder friendly design! Bolted flange and gasket would have made more sense than a silver soldered AND threaded collar/threaded stub.

Not very nice casting work in that area either. I assume the stub part of the box gets the male thread? Can't tell for sure from the photo -- is the box aluminum or cast iron? And what are the box dimensions? Is it a tapered thread, or a straight thread with gasket?

Oh, yeah, now I can see in the drawing the stub is male threaded on the outside. The brass ring thread is also stopped, another pain. It bears against the casting to seal -- so it's probably a straight thread. I hope the casting can be cleaned up enough to seal here with those casting flaws like that. And I see the name Westbury on the dwg. so that explains some things.

[stirling lad]

VT...The casting is aly minyum ,, the top square is 3"1/4 x 3"1/4 and the deck like part of it is 4"1/2 x 4"3/4,roughly,,,
I have'nt done anything to this part except use a piece of wire to get all the sand out from the water jacket cavity..
I don't know for sure but the bottom looks like it may have been filled                in at the really shiny part,, then ground off flat,ish
again...
I really like the sound of that idea about the flange and gasket...at least I might be able to progress a little again if i go that route
...because the deck part has to have 3/16ths taken off of it but even with that extra bit of room for threading, I don't think i could do it...

I better stop posting photos or the mods will shoot the boots off me...
..thanks for the good ideas...

...mike..   

[dsquire]

VT...The casting is aly minyum ,, the top square is 3"1/4 x 3"1/4 and the deck like part of it is 4"1/2 x 4"3/4,roughly,,,
.
snip
.
I better stop posting photos or the mods will shoot the boots off me...
..thanks for the good ideas...

...mike..

mike

Go ahead and post as many photos as you want or need to show/get your point across. Remember a picture is worth a 1000 words. 

Cheers 

Don

[fcheslop]

If thats the ET Westbury engine. I as already mentioned used a flange ad bolted it up with an O ring groove in the flange.
Check out the drawings I seem to remember a far amount of dead space and the hot end was specified copper
Good luck she will be a great runner.
cheers
frazer

[Bradley Simmonds]

VT...The casting is aly minyum ,, the top square is 3"1/4 x 3"1/4 and the deck like part of it is 4"1/2 x 4"3/4,roughly,,,
I have'nt done anything to this part except use a piece of wire to get all the sand out from the water jacket cavity..
I don't know for sure but the bottom looks like it may have been filled                in at the really shiny part,, then ground off flat,ish
again...
I really like the sound of that idea about the flange and gasket...at least I might be able to progress a little again if i go that route
...because the deck part has to have 3/16ths taken off of it but even with that extra bit of room for threading, I don't think i could do it...

I better stop posting photos or the mods will shoot the boots off me...
..thanks for the good ideas...

...mike..

Stirling Lad,

If you need a hand, or someone local to bounce thoughts off.  I work at a machine shop in loanhead with alot of different tools and machines at my disposal.

Brad

[vtsteam]

I think I'd pay a visit to Brad, Stirling -- helps to be able to talk things over -- with the parts in hand!

[Manxmodder]

VT...The casting is aly minyum ,, the top square is 3"1/4 x 3"1/4 and the deck like part of it is 4"1/2 x 4"3/4,roughly,,,
I have'nt done anything to this part except use a piece of wire to get all the sand out from the water jacket cavity..
I don't know for sure but the bottom looks like it may have been filled                in at the really shiny part,, then ground off flat,ish
again...
I really like the sound of that idea about the flange and gasket...at least I might be able to progress a little again if i go that route
...because the deck part has to have 3/16ths taken off of it but even with that extra bit of room for threading, I don't think i could do it...

I better stop posting photos or the mods will shoot the boots off me...
..thanks for the good ideas...

...mike..

Stirling Lad,

If you need a hand, or someone local to bounce thoughts off.  I work at a machine shop in loanhead with alot of different tools and machines at my disposal.

Brad

It's nearly TT Race week Brad. The island is starting to buzz with the anticipation of a road racing nation.....OZ   

[stirling lad]

   
 thanks for the offer of help Brad,, I used to be a lot closer to your neck of the woods,,my folks lived in Newtongrange...

Frazer,,So you've built one of these critters before? Ive been searching for years now trying to find a build log or any tips on how to proceed with this,, but ive just been plucking a part i feel capable of making from the drawings and making that,using only the mini lathe, so theres been a lot of hand sawing and filing but i think the parts should work ok..I finally got a mill but really that's just something else I've not got a clue about, along with the rotary table ,,I just wish i had someone I could visit at their workshop to watch how things are done as i think you learn so much more that way and much quicker too... anyway... do you still have your engine Frazer? as I'd love to see some photos of how you done it...   It is meant to have a copper hot cap but I was planning on changing that to stainless because of the high heat conductivity of copper but using a flange with a gasket would provide a little gap in the heat transfer path would it not? what would you recommend i made the hot cap out of.?

...M...

[Bradley Simmonds]

VT...The casting is aly minyum ,, the top square is 3"1/4 x 3"1/4 and the deck like part of it is 4"1/2 x 4"3/4,roughly,,,
I have'nt done anything to this part except use a piece of wire to get all the sand out from the water jacket cavity..
I don't know for sure but the bottom looks like it may have been filled                in at the really shiny part,, then ground off flat,ish
again...
I really like the sound of that idea about the flange and gasket...at least I might be able to progress a little again if i go that route
...because the deck part has to have 3/16ths taken off of it but even with that extra bit of room for threading, I don't think i could do it...

I better stop posting photos or the mods will shoot the boots off me...
..thanks for the good ideas...

...mike..

Stirling Lad,

If you need a hand, or someone local to bounce thoughts off.  I work at a machine shop in loanhead with alot of different tools and machines at my disposal.

Brad

It's nearly TT Race week Brad. The island is starting to buzz with the anticipation of a road racing nation.....OZ   

Heya Oz!

I can not wait for the TT!

[Bradley Simmonds]

Stirling Lad,

The offer is always on the table.  If you want I am willing come out your way and give you a hand to get your head round your machines if you want.  I just enjoy machining.

If you have got a mill you can machine that part to thickness quite easily :-) 

[stirling lad]

 Thats a very kind offer Brad but do you realise i'm in Stirling Scotland and not Stirling west Oz ?
If your in Loanhead by Bonnyrigg you have quite a commute to work each morning,,,from Melbourne...

Seriously,, that would be fantastic,, I'll get back to you soon as i'm just waiting on a couple of dry days to construct another shed
in my garden so i can get some room back in my workshop...

..Mike...

[Bradley Simmonds]

Haha yeh, im a melbourne boy born and bred, i live on the high street in old town edinburgh now :-).  Mmm didn't even know there was a Stirling in aus ;-)

[fcheslop]

Hi, sorry I no longer have the engine.
Stainless would be good for the hot end with a bronze/brass plug brazed in.Also a little groove just before the mounting flange as it helps to stop heat transfer theres a write up on Jerry Howells site.
I like to keep the hot end to about 15thou thick not always possible
If theres any plastic/toolroom shops near you see if you can scrounge a little bit of the heat proof stuff they used on the fixed half of the tool I think its called sandanyo plate its like fibre glass.
I still have the drawings somewhere .It was one of my first hot air engines.
You do realise that one will never be enough and its an addiction that totally takes over just ask David
You can tell a Stirling builder its the guy twiddling flywheels for hours looking for tight spots or dunking the new toy under water looking for air leaks
cheers
frazer

[stirling lad]

   Haha, Frazer, I'm afraid your warning comes a little too late,   I'm already hooked ....
I often see the sun coming up,,, well daylight arriving,, ( suns a bit of a rarity up here)... like this morning for instance... I'm just off to my bed now....for some badly needed beauty sleep......(04.10 am)

...mike... zzzzzzzzzzz

[fcheslop]

yeah i know it takes you guys two weeks holiday to from blue to pink
although with my name i better keep quite
cheers