Drill & solder a cylinder , or use a liner ?

[student123]

I'm on my first engine build, the 'brassy babe':

http://www.davegoodfellow.com/plans.pdf
steam wobbler, I'm using mostly aliminium. I think I've got the cylinder wrong (somewhat oval shaped blind hole). Ok .. so try again...

I've been told that the preferred way of getting a good cylinder is to drill all the way throught the cylinder block , ream out to create a smooth internal wall, then cap the end, by soldering. This would mean switching from ali to brass ("brass is easier to solder"), buying a reamer, tools to heat up brass, & learning how to solder brass, but ok.

An alternative could be to use a liner:
http://www.homemodelenginemachinist.com/index.php?topic=5151.0

is either approach likely to be better?

Mike

 

[Shopguy]

Hi
I like to use liners for the simple reason it is a way to easily get a smooth finish in a cylinder. I've used used brass and seamless steel as liners. If you have a cylinder block made of aluminium using Loctite to hold the liner in place should work.
Regards
Ernie J

 

[student123]

Ernie,

Thanks. Presumably just a bit of brass tubing? Any min wall thickness?
would ali tubing suffice as an altrnative?

Mike

 

[Deanofid]

Mike, this engine should not/does not need a liner, and you are talking about going through an number of hoops to get a simple hole. I think you should examine your cylinder piece and find out why you got an oval hole, if indeed, you did. This cylinder bore can be done easily and properly with a regular chucking reamer, or a shop made D-bit, and probably even a regular drill bit.

Dean

 

[Shopguy]

I've used very thin brass seamless tubing. However, as Dean has mentioned you need to find out why you ended up with an oval hole. Is something moving when you are making this bore? You didn't say how you made this hole, you can sometimes end up with funny holes if you use a drill bit that is sharpened wrong.
Ernie J

 

[Deanofid]

I think Ernie may have the reason for your hole being oddly shaped, Mike. You may be able to ream the hole you have now and end up with it being fully usable. You would just have to make your piston a little larger in diameter to take up for any slack in the dimension of the hole made by reaming it.

Good luck with your project. Keep us posted, and ask all the questions you like.

Dean

 

[student123]

Ernie & Dean,

Thanks for the replies.

You didn't say how you made this hole, you can sometimes end up with funny holes if you use a drill bit that is sharpened wrong.
Ernie J

Started this a while back, broke off while I did other things.
Would have used my then new bench drill & one of the new twist drill bits I bought with it. At the time I didnt then know about centre drill bits.

Looks like the way forward is the simple reaming approach. I have to remake the piston anyway.

 

[Swarf Rat]

Perhaps another option would be to drill and ream through and then fasten an endcap.

 

[Shopguy]

Mike
Sounds like you are getting things sorted out. Reaming works too. Don't get discouraged about remaking parts, we all make lots of pieces that don't work or fit.
Keep at it and your engine will turn out
Ernie J