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Member postings for Martin Green 3

Here is a list of all the postings Martin Green 3 has made in our forums. Click on a thread name to jump to the thread.

Thread: Cylinder boring
05/11/2018 18:18:51

Everyone has given me really good ideas I will pause for a while on this post and experiment. From the support I have been given I know where to come when I want more help.

Thanks again.

05/11/2018 15:44:07

I have just been in my workshop trying out the aluminium cutter in my boring head. The finish is substantially better than using the standard indexable cutter. However it is not really smooth.

I note from Fowlers Fury says

"However, as Paul K comments " cast iron can be a very variable material............." I've just finished boring out CI cylinders to similar dimensions as yours, sold by one of our suppliers and the CI has machined much less cleanly than previous castings I've purchased. Surface finish even after much honing is relatively "rough"."

The milled surfaces of the castings although smooth when finished with emery are not as good as the wheel casting finishes. They look as if there are slight pits in them. My wheels look lovely. I would add that the castings for the wheels as over 30 years old and the cylinder casting are less than 6 months old.

My problem is I do not know if I can expect a better finish.

I will hone the cylinders but has anyone any suggestions as to the finish I should be able to achieve?

05/11/2018 13:00:45

I am coming to the same conclusion as all of you. Although the boring bar is 12mm in diameter it can flex easily when stressed. The lateral movement can be substantial.

However I will try a light cut using my aluminium cutting tool and if that works then fine. I suspect I will have to go to the boring bar solution.

Fowler, I think you should have an apostrophe in you name...!!! Thanks for the photo they are very informative.

Can you point me to Geo Thomas's boring bar design?

05/11/2018 12:18:21

Thanks for your thoughts. The mill is a Chester mill and seems to perform all the other functions accurately. The indexable tool is in an adjustable boring head and is about 6in long when inserted in the head. I have an insert for cutting aluminium and will try that.

From the comments above it would seem that very light finishing cuts at slow speed with a very sharp tool is the solution.

Would you agree?

05/11/2018 11:06:03

I am boring my first cylinder in cast iron using my mill. I have machined all the surfaces and the finish looks fine. However when I take a cut in the cylinder bore using my standard boring head the surface finish is awful. It looks as though the tool has juddered. I have tried slowing the cutting speed. I am running at about 500 rpm and the head is moving very slowly.

I am using an indexable tool and the bore finish size is 1 3/4in and cylinder length is 3 1/4in.

Can anyone suggest a solution?

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