can i drill offseth with a 4 jaw chuck??

[larsinist]

I am making a stirling engine cylinder,and only have 24mm drill,and i need my cylinder diameter to be about 40mm, and i have no long cutter tool that is for inside drilling.
but i have a 4 jaw chuck, can i use a drill in the tailstock, and then place the cylinder in offseth,is that possible??,will the drill be able to make the hole bigger????
or is the only way to have a long cutter tool?

Sorry my bad english

Regards:Lars

 

[modelman1838]

Lars
No that will not work, you will still only drill a 24 mm hole on the axis of the lathe. As you are making a stirling engine cylinder you will need a great deal of precision so you will have to drill 24mm and then open up this hole with a boring bar until almost to size and then make an expanding lap to provide a suitable finish which will need to be perfectly round and parallel to suit the piston. Boring tools and laps are items that you can easily make yourself and usually are, but you may need to do a bit of reading up on the subject.
Best of luck Hugh

 

[larsinist]

Lars
No that will not work, you will still only drill a 24 mm hole on the axis of the lathe. As you are making a stirling engine cylinder you will need a great deal of precision so you will have to drill 24mm and then open up this hole with a boring bar until almost to size and then make an expanding lap to provide a suitable finish which will need to be perfectly round and parallel to suit the piston. Boring tools and laps are items that you can easily make yourself and usually are, but you may need to do a bit of reading up on the subject.
Best of luck Hugh

Thanks for answer, i have build many tin cans stirlings, but now i want to try build a better one."see pic of cylinder" i will get a boring bar tomorrow,and i will try to do it right,but what is a expanding lap??i think i need 1.5mm-2mm clearance between the cylinder and the piston.am i wrong here??
The cylinder bore shall be 40mm, so the lenght of the cylinder should be 125mm-130mm and the piston should be 80mm,am i right here???



Lars

 

[larsinist]

I have found this boring bar, do you think i can use it??
http://www.maritool.com/Indexable-T...STEEL-BORING-BAR-.625-shank/product_info.html
My cutting steal is 10mm, so i think i need a boreing bar that is 10mm.
i also need some Insert to it, so if someone can link me that it have been great

And do i need a boring bar holder??
sorry for all my naging, but i need some help

Lars

 

[kvom]

A boring bar can only enlarge a hole that is already larger then the shank size. Since 24mm is about 1" and since that bar's shank is .625 it will work if you drill the hole first with the 24mm drill bit.

You should be able to buy inserts that fit the bar from the same vendor. In any case the insert type is specified.

It appears that your toolpost is one that holds 4 tools via screws; boring bar has a flat on the top to ensure that the insert is held at the proper angle, so if there is space for the bar to fit in the holder slot, then the set screws will tighten down onto the flat.

It will be easier to make a piston to fit the bore than vise versa.

The bar will hang out a lot, so it will not be totally rigid. You should have the final pass be very small and do several spring passes to avoid a tapered hole. If a 3/4" boring bar will fit the tool post you might consider going larger for extra rigidity.