Dividing Head

[Bezalel]

I see this little project a continuation of my Wallaby 30cc IC build. 
 
I need to cut a few gears for the oil  pump and timing gears etc.
 
I don't have a dividing head so this will be my attempt make the kit I need. 
 
I went for a version of Harold Halls dividing head as seen in Workshop Practice Series books 35 and 37 IIRC.   
 
First problem    was getting the right size stock for project.
 
I have a length of 38mm BMS about 125mm long that will do nicely for the spindle, but the body is proving to be a challenge.
 
So I have opted to cast the body and foot plate all in one piece  and add a bit to all dimensions.
 
I hope it doesn't stuff up anything critical in the basic design. I can't see how it can............ !!!! Yet !!!!
 
I'll get some photos sorted and put them up soon.

[steamer]

Sounds like a perfect approach to me!.....I'm in!

Dave

[metalmad]

HI mate
Is any project really finished?
Im still doing little things on all my Engines including the Wallaby
Pete

[steamer]

Hey Pete!

Congrats on the Project of the Month on HMEM!

Well earned!

Dave

[metalmad]

Thanks Dave 
Pete

[Bezalel]

The pictures are in ( there was a time we had to take a little can to the pharmacy and the wait 3 weeks to find out how many were in focus - ain't digital great)
 
Here is the body pattern
 

 
and of course to get  the pattern out of the mold easily this one is a split pattern.
 
As you can see I am going for a pretty heavy cross-section  to help with rigidity.
 

 
I will be using ZA27 Alloy because of its properties having a close similarity to cast Iron plus I won't need to  insert bearings as the casting itself will have excelant bearing properties.
 
Ah-ooooh......... I see in the photo date the photos were taken tomorrow. I was wondering what I will be doing tommorrow - now I know 

[steamer]

Thanks Dave 
Pete

Absolutely well deserved Pete....I know how much hard work goes into that!   Really Well done!

Dave

[steamer]

Bez,

Those patterns are beautiful!   Any pictures of the fab?   

Dave

[Bezalel]

G'day Dave,
 
Hi Pete - Congrats from me too, I would have  done it on the other place but unfortunately Bezalel is no  longer permitted to post there.
 
Never mind the company here is pretty good too. And they still let me post 
 
First  casting was a miss pour - not enough weight on the cope.   
 
I forgot...... ZA27 is double the weight of Silicon Ali and I only had the usual weights on the mold and the hydrostatic pressure  Just lifted the cope clean off the drag. giving me half a casting and one very large sheet of ZA27.   
 
Second Pour went much better with 6 x 16mm steel plates holding every thing down.
 
I milled the top and bottom surfaces parallel then chucked in the the 4 jaw.
 

 
I had to run  the lathe quite slow to bore her out because of the huge imbalance - did I mention ZA27 is heavy?
 
I wanted to  mount it on the face plate so I could balance it with a counter weight, but that was turning into a project all of its own so I took the shorter route.
 
I'm now heading back to the Pharmacy  camera to get some more photos.
 
Bez     
 
 
 

[steamer]

Cool!   Keep it coming Bez!   I made a little one a number of years ago that I used alot....but of brass....They do come in handy!


Dave

[Bezalel]

Hay Dave, by fab do you mean fabrication technique/method?
 
I'll answer that question any way. Sorry I didn't take any photos it all happened pretty quick.
 
To make the pattern into its final shape was more of an evolutionary process than detailed design.
 
It is a bit of a rough-n-ready, to be honest
 
Each side was built separately and the first side was just duplicated.
 
I took a sheet of 16mm mdf and cut out a piece that would fit across two T slots of my mill table.
Then took two pieces  about 40mm wide by 125mm long superglued them together banged in a nail or two to hold it all in place so I could shape it on the linisher putting a draft taper on all sides by eye.
 
after sealing and sanding ready to make a mold I thought I want to use a cotter pin type spindle clamp, but there is probably not enough room along side the spindle to do that.  The solution was to cut 4 off 6mm mdf pieces and glue them each side of each pattern half - that explains the interesting shape.
 
The filleting is just a plaster type wood filler. then the whole thing was sealed again and the mold made.
 
The gating system was totally inadequate for such a huge chunk of a casting so there is quite a dip in the casting on the side facing the chuck  but I was able to trim it square while it as bolted to the mill table.
 
The next bit was to center up the spindle blank in the four jaw and centre drill it ready for a later operation.
Then flip it over and center it up again.  Then drill and bore a 15mm core almost to the centre hole at the other end.
Adjust the compound slide to bore the 8 deg taper for an ER Collet. I would have liked to use ER32 but the blank was less than the 40mm needed to cut the nut thread. (only 38mm  )
 

 
 
 ER25 will be OK and the nut thread is only 32x1.5mm.
 
This is where we are at now. Waiting for an ER25 nut
 

 
Thanks for dropping in.
 
Bez
 
 

[Don1966]

That is some impressive bit of work Bez and very interesting. I will be pulling up a chair for this one. I had built a furnace and only melted metal in it, just haven't cast anything yet. Still learning how to do it. I do have the sand, coupe and drag.

Don