stragenmitsuko
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- Jan 19, 2016
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So I need to bore a 1-3/4 by 2.5" ( 64*45mm) aluminium block with a length of 6" ( 150mm) .
Bore needs to be parallel to at least one surface , altough that could be milled later on .
Bore diam would be 1.40" ( 36mm ) .
As this will be a cilinder for a gas engine , some degree of acuracy is required , altough a liner will be pressed in afterwards .
Option A : hold it in a 4 jaw , that would leave abt 4" sticking out .
I can hold it in the 4 jaw , but it won't pass the bore in the chuck .
Then use a heavy boring bar and machine to size .
Option B : clamp it to the mill table , and use the mill in horizontal setup
in combination with a boring head and again a large boring bar .
Option C would be to line bore it , wich would be the best option by far .
But helas , none of my machines will allow this .
Thoughts :
In the lathe the bore can be finished to closer tolerances , and most likely better finish . But parallelism
to the surfaces can't be guaranteed . I know I can indicate it but still . It'll be only an 1-1/4 (30mm) in the jaws .
If the block is a bit oversized maybe it can be milled afterwards to produce the surfaces parallel to the bore .
On the mill however , clamped to the table the bore will be parallel to the table , but with a boring head I'll be lucky to
obtain the correct dimension and avoid boring a taper .
So none of these options really pleases me , but I need to make a decision on this .
Normally one would use cast iron for a cilinder . Wich I don't have , and can't obtain .
So I thought I'de use an ali body and press in a sleeve .
Can I use steel for the sleeve ? Same problem , don't have any cast available .
Thougt maybe I'de use seamless black pipe to make the sleeve .
The piston is aluminium with cast iron rings .
Sleeve offcourse will be honed or lapped once the cilinder is finished .
It will also require carefull machining to obtain a decent press fit , but that
is possible with the machines I have .
The black pipe will pass the chuck body to bore the inside , then it can be put on a mandrel to machine the outside .
Thx
Pat
Bore needs to be parallel to at least one surface , altough that could be milled later on .
Bore diam would be 1.40" ( 36mm ) .
As this will be a cilinder for a gas engine , some degree of acuracy is required , altough a liner will be pressed in afterwards .
Option A : hold it in a 4 jaw , that would leave abt 4" sticking out .
I can hold it in the 4 jaw , but it won't pass the bore in the chuck .
Then use a heavy boring bar and machine to size .
Option B : clamp it to the mill table , and use the mill in horizontal setup
in combination with a boring head and again a large boring bar .
Option C would be to line bore it , wich would be the best option by far .
But helas , none of my machines will allow this .
Thoughts :
In the lathe the bore can be finished to closer tolerances , and most likely better finish . But parallelism
to the surfaces can't be guaranteed . I know I can indicate it but still . It'll be only an 1-1/4 (30mm) in the jaws .
If the block is a bit oversized maybe it can be milled afterwards to produce the surfaces parallel to the bore .
On the mill however , clamped to the table the bore will be parallel to the table , but with a boring head I'll be lucky to
obtain the correct dimension and avoid boring a taper .
So none of these options really pleases me , but I need to make a decision on this .
Normally one would use cast iron for a cilinder . Wich I don't have , and can't obtain .
So I thought I'de use an ali body and press in a sleeve .
Can I use steel for the sleeve ? Same problem , don't have any cast available .
Thougt maybe I'de use seamless black pipe to make the sleeve .
The piston is aluminium with cast iron rings .
Sleeve offcourse will be honed or lapped once the cilinder is finished .
It will also require carefull machining to obtain a decent press fit , but that
is possible with the machines I have .
The black pipe will pass the chuck body to bore the inside , then it can be put on a mandrel to machine the outside .
Thx
Pat