MadModder
Gallery, Projects and General => The Design Shop => Topic started by: Will_D on November 02, 2014, 03:31:37 PM
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I need to machine some concave cuts into a set of pinch rollers.
The rollers are used to roll copper tubing into fairly tight coils. I need to cut 8mm, 10mm and 15mm concave grooves into the steel rollers.
Rather than use form tools ( even tho' the misses is a bit deaf the chatter would be unacceptable) I fancy the Repton ( from Cronos http://www.chronos.ltd.uk/engineering-tools/2013/2562/ (http://www.chronos.ltd.uk/engineering-tools/2013/2562/). They state a maximum capacity (both Concave and Balls) but no minimum.
As there is a tenner off the price I am sorely tempted.
Does any one here have one? Can it cut a 8mm concave half circle out of steel?
Can it make me a new set of balls out of 316 SS? (XXXL Please)
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the simple answer is no.
to be able to turn a semi circle , the whole tool has to be no more than the diameter.
This is the setup i used to make some larger pipe benders.You may be able make a smaller one that will do your job:)
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Simply answered is yes
But they are very poor lots of chatter ,difficult to set up and leave a poor finish
It's a poor design , A very poor purchase on my part
I get much better results from a Hemmingway kit over under type that uses a HSS tool bit .
I think it's the use of a insert tip that contributes to the Reston poor finish
That my take for what it worth
Stuart
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yes? 8mm?
is that thing really so small?
bill
[edit]
another thought...
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Stuart,
I can't see how the Hemingway spherical turner can do what Will_D wants as it stands. It looks as though when mounted in a tool holder it will present the tool at centre height. This is fine for turning balls but for cutting grooves in rollers you would need to be able to adjust the height. Maybe mounting to a vertical slide would help but then you're losing out on rigidity.
I would be tempted to go for a vertical axis type which would take most of the cutting forces down through the cross slide and the bed of the lathe. A tool bit like in the Hemingway kit would allow you to cut small(ish) radii.
Phil
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Thanks for the comments. Will save the wonga for another project. At the moment I am back to:
X^2 + Y^2 = r^2 (Eqatuon of the circle.
Now used xcel to set out a set of X,Y coordinates and then uses a small parting tool to do the roughing. Then send then misses shopping and in goes the form tool ( Have two ground up: HSS and also TC)
I do like the look of Bill Todds set up but to make a small rigid version (to cut a 8mm semi circle) would be a challenge but hey we are engineers!