Twin Grasshoppers

[crueby]

Excellent - great motion on the beams/etc.   

[vtsteam]

Looks really fine! 

[Kim]

Love seeing it all going around!  It feels mighty good, doesn't it?! 

Kim

[Chipmaster]

Thanks chaps.

I had a go at the parallel motion links next.

Parallel Motion Link and Pin by Andy, on Flickr

Flat steel strips were used on the original model but I decided to try making round rods as seen on some excellent model grasshopper engines. However, I didn't want the complication of split bearings at each end so my rods would have plain bearings.
12mm square bar was the most appropriate steel to hand. After drilling and reaming the 3/16" holes the bars were turned down to 0.2" diameter.

The first pair were turned between centres and finished off in a three jaw chuck.

IMG_5874 by Andy, on Flickr

After machining in the lathe the 12mm thick ends were milled down to 3/16" thick. (Flickr video)

 Twin Grasshopper Beam Engine by Andy, on Flickr

Twin Grasshopper Beam Engine by Andy, on Flickr

Followed by an attempt to round the ends.....reckon some more work is needed to improve the appearance.

Twin Grasshopper Beam Engine by Andy, on Flickr

For the second pair of links I decided not to faff about turning between centres but to hold the bar in a four jaw self centring chuck and speed the lathe up. It's an Charles Taylor chuck, made in Birmingham, accurate with a very strong grip but also very heavy so I don't use it much.

 IMG_5902 by Andy, on Flickr

IMG_5903 by Andy, on Flickr

Charles Taylor chuck in action with an old Cintride tool, are these tools still made? I have several that a college had thrown away in a skip.

IMG_5904 by Andy, on Flickr

I left the bolts and filing buttons in position as guides for where to stop and start with the tool. The second pair of rods were machined very quickly, I hope to round the ends tomorrow.

Andy

[vtsteam]

I like old tooling. I don't know what a Cintride tool is. Some kind of sintered carbide? That chuck looks impressive and the chuck key is even more so. It shows a lot of confidence by a chuck manufacturer to include a key like that! 

[ettingtonliam]

I shouldn't think those Cintride tools are made in this age of throw away tips. I've got a left crank, a right crank and a straight, had them for about 40 years, and probably do 90% of my turning with them. Easy to sharpen on a green grit wheel.

I think Cintride was the trade name for them, tungsten carbide tips brazed onto the shank.
Looking at one of mine, the left hand crank, it has 'Cintride England' stamped on one side of the shank, and 12/E183/5TR on the other. No I don't have a clue what it means!

[samc88]

Looking very impressive! My Colchester has a 3 jaw chuck by them, very nicely made bit of kit

[john mills]

those chucks were the ones on the repco crank shaft grinders usually tightened with length of pipe on that chuck key
John

[Dalboy]

A good looking build will be watching this until the end

[Chipmaster]

Hi John, so the Taylor chucks were well travelled.

I looked up Charles Taylor chucks on the internet and the firm appear to have made chucks until the 1970s. The lathes.uk website states ..."the Taylor 2, 3 and 4-jaw self-centring chucks were, at one time, considered the "Rolls-Royce" of the type and featured a conical "taper-scroll"

http://www.lathes.co.uk/taylor/page3.html

At our Wednesday steam club (now reduced to two of us) meeting this afternoon my friend had a go at lifting the Taylor chuck but he couldn't lift it very far 

I rounded the ends of the parallel motion link rods this morning but they're not good enough to show yet.

Liam, Cintride Ltd appear to have been in Derbyshire and closed down around 20 years ago.

Andy

[Chipmaster]

I made the two pairs of parallel motion links according to the drawings exactly 4.5/8" between centres which matched the spacing of the holes in the beams all drilled by me.
However when I tried to fit the parallel motion links to the assembled engine I found the mounts for the pivots in the triangular 'motion brackets' on top of the cylinders were about fifty thou out of position horizontally too far back, not in line with the centre line of the piston rods so it couldn't move.

In these pictures I have a thin rod through the 5/16" hole in the beams to illustrate the discrepancy.

 Twin Grasshopper Beam Engine by Andy, on Flickr

Twin Grasshopper Beam Engine by Andy, on Flickr

I carried on and made the pivot that passes through the centre of the beam.

 Twin Grasshopper Beam Engine by Andy, on Flickr

Twin Grasshopper Beam Engine by Andy, on Flickr

My next move is to try a bodge by elongating the 1/8" holes in the !/2" thick brass motion brackets.

You can see in this picture that the slot will come out the side of the casting if I'm not careful. The 1/8" endmill flexed and produced an elliptical hole rather than a slot.

 IMG_5940 (3) by Andy, on Flickr

A washer can cover that.

IMG_5942 (2) by Andy, on Flickr

I didn't have time to see whether the bodge will work, I'll have to mill a slot in the other motion bracket tomorrow. If there isn't enough casting left for the necessary elongated slot then I'll solder some more brass on to the edge of the casting.
P.S. I considered turning the motion brackets round to gain more meat for repositioning the pivot holes but that introduced too many extra complications.
To be continued
Andy

[crueby]

Would it be possible to elongate the mounting holes at the bottom of the brackets to shift the brackets rather than the top holes?

[Chipmaster]

Hi Chris, thanks for your thoughts. I don't understand where I went wrong but the problem was solved by elongating the holes in the opposite direction away from the edges of the motion brackets, it seemed so clear what needed to be done when I posted yesterday evening. I hope I'm not going barmy 

This morning I elongated the slots using a shorter more rigid 1/8 slot drill and the parallel motion works, reckon I have been lucky with that  As you can see in the picture moving the two triangular motion brackets could have upset the appearance as they fit up to the edges of the cylinders at the moment and they're also shaped to clear the curvature of the cylinder cover by a small amount.

Twin Grasshopper Beam Engine by Andy, on Flickr

Apart from the gap that will need to be covered or filled plus the dings in the edges of the casting caused by the milling vice things don't look too bad.

Twin Grasshopper Beam Engine by Andy, on Flickr

Twin Grasshopper Beam Engine by Andy, on Flickr

Twin Grasshopper Beam Engine by Andy, on Flickr

Now the process will be repeated on the other engine, hopefully with more finesse next time.

Andy

[Sevenmpd]

Looks an interesting build look forward to following it progress 

[Chipmaster]

Cheers H 

Andy