Walking Beam Stirling kit cylinder concerns.

[kcmillin]

A few months ago my freind bought a walking beam stirling engine kit from Grizzly. also available at Littlemachineshop.com.

My concern with this is the aluminum cylinder. It came with a 13mm piston already made, and the cylinder needs to be made. It is a blind hole.

I have never used aluminum for a cylinder.

What should I use to make the bore? He bought a 13mm drill bit for this purpose, but I worry this would leave a bad hole. I also have a boring head, but no real accurate way of measuring the bore. In th past I have always made the cylinder first, and then fit the piston to it.

So, has anybody built this? If so, how did you make the bore for the brass piston?

kel

PS.
This might seem backwards and stupid, but what If I used the boring head to bore the hole to a few though less than 13mm and then used the 13mm drill bit to finish the hole to size?

 

[Metal Butcher]

The piston to bore fit needs a high degree of accuracy and smooth surfacing for a sterling cycle type engine.

Since 'drilling' is a roughing operation it should only be used as a first step in producing a cylinder bore.

The usual steps are to drill and bore, or drill and ream. Either way, the finishing step would be to either lap or hone.

Would it be possible to make you own piston, and simplify the process of achieving an acceptable piston to bore fit?

If I may, I would suggest buying a set of 'telescopic bore gauges'. They are really handy for measuring bored holes. Being inexpensive but indispensable, every shop should have a set on hand.

http://www.grizzly.com/products/Telescopic-Gauge-Set/G5656

-MB

 

[Deanofid]

I would make a D-reamer for it. You can make it to a very precise size without much trouble. It will make a very straight hole.

Check it on a scrap piece of aluminum to see that you get a good fit for the piston, then make your "for real" cylinder.

Another thought; If the piston they sent you is of a shape that you can machine it further, then do the bore in your cylinder to about a thou under size, and finish off the piston to fit.

Dean

 

[Quake]

I got the same kit.

For anyone interested, here's the link to the material kit complete with free PDF plans you can download:

http://www.grizzly.com/products/Horizontal-Stirling-Engine-Kit/H8101

There are no castings - mostly bar stock, with some hex rod & flat bar and fasteners. It's metric and, as is the case with most hot air & Stirling engines, tolerances tend to be tight compared to other model engines.

Referring to page 9 of the manual, which piston are you talking about? #45 or #16?

Mine came with #45 piston and the #21 cylinder completed - those are the displacer piston/cylinder and MUST NOT be a tight fit. The other piston/cylinder in my material kit are not finished at all.

I haven't built mine yet - planning to start this week or next (gotta get my new Grizzly lathe set up and ready to go) - so it is possible that I have misunderstood something.

 

[Quake]

I got to looking at my kit & plans last night and you are correct - both pistons are 'pre-finished'.

When I build my kit, I'm going to stick to the normal process - I'll make the cylinder first, and if the pre-finished piston doesn't fit, I'll just make a new one. Mine is a little tarnished after sitting for a while anyways.

 

[kcmillin]

I got to looking at my kit & plans last night and you are correct - both pistons are 'pre-finished'.

When I build my kit, I'm going to stick to the normal process - I'll make the cylinder first, and if the pre-finished piston doesn't fit, I'll just make a new one. Mine is a little tarnished after sitting for a while anyways.

Yep, that is what we plan to do.

Thanks,

kel