Milling a mast cap

[No Idea]

Here’s another example to help you though this time the head is in the horizontal position. I’m milling the cap for a bow bollard and I also cut a shallow rebate in it too.  Have the cutter at high speed and take lots of shallow cuts. After I had cut the correct diameter I then set the head vertically and milled the correct thickness. 

[Bob Cleek]

3 hours ago, wefalck said:

Two additional comments on the above:

 

- rotate the rotary table always against the rotational direction of the mill ! These rotary tables are not actually meant for round-milling, but for indexing. If you rotate the table the other way around, the mill can grap the workpiece and wrench it from your hand. For this reason it is also advisable to let the locking knob slightly bind, so that there is a bit of frictional resistance. That helps to steady the movement.

And: do not try to do this kind of operation with metal ! Real rotary table built for round-milling have a self-locking worm-drive.

 

- I would make the first cut a bit wider (on the outside) and narrower (on the inside) and go for second, finishing pass.

If I could have given two "thumbs up," I would have. Wood is much more forgiving than metal, but safe procedures should always be followed no matter what. A broken mill bit can be a somewhat costly accident, but a broken piece of bit launched towards the operator's face can result in a problem money can't fix.

[wefalck]

Incidentally, there is another, much safer way to mill a round on an indexer: take repeated tangential or longitudinal, if the axis of the indexer is horizontal, cuts, advancing the indexer 5° degrees or so every time and locking(!) it. This is best done, if the blank is just a tad bigger than the final part. So cut the blank to size first on a table saw or by hand. The final pass on the mill, to really smooth it, then can be done by turning the chuck.

I use this procedure to make half-round parts or for rounding-off corners. This procedure is also safe with metals, because you lock the indexer every time you take a cut and your hands are away from the milling cutter.

 

On safety: always wear safety glasses - more important than on a lathe, because the chips fly around much farther and often into the direction of the operator. On a lathe the chips tend to be projected downwards towards the operator, who usually looks down onto the work.

 

 

[stuglo]

2 hours ago, DelF said:

Hi Stuglo

 

I wouldn't use the rotating table in the vertical mode to mill anything more than a centimetre or two in length for the reason you state. I tend to use it in the vertical position to do things like these columns. I turned them on a lathe, but then used the dividing head to mill the grooves to give a fluted effect. Basically, you lock the table in place, mill the first groove, then rotate the workpiece a set number of degrees ( for example 60 degrees if you want six grooves) and repeat. Most of the other elements of this boat support were made on the mill. I should point out that I eventually replaced the overscale belaying pins!

 

It's difficult to see on this photo, but I also used the dividing head to mill the slots for the spiral steps just visible on the right. Similar principle.

 

Derek

 

August 2019_0034_edited-1.xmp 6.8 kB · 1 download

You've taught me a lot. But I'm greedy. Please keep posting whenever possible. (That fluting- stupid of me not to have thought of it )

[glbarlow]

4 hours ago, DelF said:

other elements of this boat support were made on the mill

That’s real skill Derek, very nice work. So much there you’d never see in a straight up kit. I learn a lot from your well explained examples. 

[glbarlow]

4 hours ago, allanyed said:

a canvas cover.

I haven’t seen any of the Cheerful builds this way, I think I’ll go with the “trim ring” however accurate it may or not be. 

[glbarlow]

I appreciate all the comments for my mis-labeled post. But let’s assume I’m a grown-up and understand the basics of machine shop safety. Also, I have no intention or need for any metal work. The two vices I have are specifically designed for my Proxxon mill and are highly rated by it’s users so I’m ok on that front too.  
 

I now have good examples of two ways, and can use both for more than just a trim ring - very cool stuff
 

I agree I just need to get in there and cut something. Or maybe fly across the pond and buy a few beers at the pub for Derek -after- he shows me a few things (see, shop safety right there;-) But for now my focus is on finishing planking on Cheerful, I ripped 40-50 more yellow cedar planks last night and will likely need most of them to finish the hull. 
 

I’ve bookmarked this thread and will keep it handy. If anyone want to follow Derek and No Idea’s tutorials (Maybe an actual mast cap:-D) with their own please do. We’ll all benefit.