Milling a mast cap

[glbarlow]

I have a new Proxxon mill I don’t know how to use yet. One thing I want to learn to do is to use the rotating clamp to mill a nice mast cap.  Anyone have an example or a source/reference I can look to?

[wefalck]

A couple of questions upfront:

 

- what do you mean by ‘rotating clamp’ ?

- what material do you use for the cap

- what milling cutters do you have ?

 

A mast cap seems to be a rather complex project to start with, btw.

[glbarlow]

The dividing attachment for the Proxxon FF 70

The Proxxon cutters and a selection of smaller ones. Using Yellow Cedar.  
 

Im sure your right, I’ll find a simpler way. 

[wefalck]

OK. The clamping is a bit complicated by the fact that you presumably will have a rectangular part, but you have 3-jaw-chuck. It would be possible, but is not so simple.

 

I don't know, whether the 3-jaw-chuck in the dividing head can be changed for one of the independent 4-jaw-chucks PROXXON offers, if I am not mistaken. That would be a better starting point.

 

However, I think using a simple vice would be a lot easier. If you don't have one yet, get yourself what is called a 1" 'toolmaker insert vice':

 

Image from: https://bahrain.desertcart.com/products/58940869-accusize-tools-mini-precision-toolmakers-insert-vises-ga-41-0050

 

They are very good and more precise than the PROXXON vices. They should cost around 30  USD on ebay etc.

 

You would cut a piece of wood that is a bit larger than the cap, but considerably longer, so that you have a sort of 'stem'. In the first step you would mill the four sides, while the part is clamped with the stem. For this you don't need to move the part, all movements are done with the slides. In the next step you drill down whatever holes are required - square holes can be finished with a fine file later. In the third step you turn the part in the vice on its side, so that the top of the cap protrudes sideways, which allows you to mill its profile. For this you will have to make yourself a chart for the necessary movements of the slides. Finally you saw off the cap from its stem.

[stuglo]

I'm disappointed with the 3 jaw dividing attachment as I have not found a way to central a non round piece. Can anyone advise?

Also I checked these on these accusize vices and the advantage isn't obvious to me if I use an X-Y-Z table- please could you explain

[No Idea]

This can be done quite easily with the dividing head that you have.  You can turn it by hand once the job is locked into the vice just mind your fingers.  If the piece you want to cut is not round, glue it to a piece of round dowelling to mount it onto the dividing head.  Once you have finished machining cut it away from the dowel and clean it up.

[wefalck]

Well, 3-jaw-chucks are made to center round objects

 

If you want to clamp differently shaped objects, you would need an independently adjustable 4-jaw-chuck. This means each jaw can be moved independently, so that you can move a part around the chuck until you have the point you want centred (within the size limits of the chuck).

 

The second question I don't understand. What do you mean by 'accusize vice' ? In any case you will need either clamps (of which there are wide variety of shapes and sizes) or a vice to clamp a part to your x-y-table. A vice is the more common and versatile way probably, as its faces can be carefully aligned to the axes of the table, so that the faces of parts are aligned too.

[wefalck]

1 minute ago, No Idea said:

This can be done quite easily with the dividing head that you have.  You can turn it by hand once the job is locked into the vice just mind your fingers.  If the piece you want to cut is not round, glue it to a piece of round dowelling to mount it onto the dividing head.  Once you have finished machining cut it away from the dowel and clean it up.

I do this also with metal, btw. One can solder a spigot to any part so that it can be held in a 3-jaw-chuck or collet for machining. For smaller parts I just use a big enough diameter round brass - a bit wasteful, but safe and simple.

[No Idea]

Hi wefalck yes I do this with metal too.  I have this milling machine and dividing head and with limited tooling comes imagination.  If I'm gluing or soldering my piece to a dowel to rod to get it in the dividing head I leave it thicker than the finished article.  That way when I do remove the mount if it takes a bit of the job with it I still have plenty of material left to clean it up.  I also have the proxxon vice and for the MF70 mill its more than adequate if a bit over priced for what it is.  Its a great mill for wood mainly because of the very high spindle speeds.

[DelF]

10 minutes ago, No Idea said:

If the piece you want to cut is not round, glue it to a piece of round dowelling to mount it onto the dividing head.

This method works really well with the Proxxon dividing head. For example to create wooden rings for mast hoops or whatever, I superglue a piece of sheet material of the required thickness and size to a dowel (the sheet can be any shape so long as you can get the required outside diameter out of it). Once clamped in the dividing head you mill to the outside diameter then the inside and hey presto you've got a ring. If the outside of the ring needs to be chamfered you can do that before milling the inside diameter.

 

53 minutes ago, wefalck said:

and more precise than the PROXXON vices

If you're talking about the standard Proxxon vices I would agree. However the  precision machine vices are more than adequate for milling purposes. This is the PM40:

 

 

Derek

[wefalck]

Still too big for a lot of milling jobs around models. Note that the toolmakers vice has recesses at the top of the jaws that allow you to safely clamp smaller pieces without the aid of 'parallels' underneath. The recesses are about 2 mm x 2 mm.

[No Idea]

Hi DelF I have to agree with you its a very good bit of kit for what we need.  Here's a ring a cut from 3mm boxwood I think it came out ok

[Bob Cleek]

44 minutes ago, DelF said:

For example to create wooden rings for mast hoops or whatever, I superglue a piece of sheet material of the required thickness and size to a dowel (the sheet can be any shape so long as you can get the required outside diameter out of it). Once clamped in the dividing head you mill to the outside diameter then the inside and hey presto you've got a ring. If the outside of the ring needs to be chamfered you can do that before milling the inside diameter.

That sounds like a hard way to do it. I take a mandrel ("stick") of the proper inside diameter of the mast hoop I want to make and wrap a piece of plastic kitchen wrap around it so glue won't stick to it.  Then I take a nice straight grained piece of wood and plane six or eight inch shavings off the edge of it. Then, applying PVA glue as I go, I wrap the shavings tightly around the mandrel and fasten them with a rubber band and let the glue set. After the glue is dry, I mount the mandrel on my lathe and sand the face of the shavings fair, then I part off the rings with a knife or jeweler's saw, leaving the hoops on the mandrel as I go. I then round the outer edges of the hoops with a file on the lathe if needed or just lightly sand to knock off he corners, depending on what I want it to look like. I then slide the rings off the mandrel and clean up the inner faces and edges with a bit of sandpaper by hand. This method produces hoops made of fine laminations which will not break on the grain, as do hoops cut from any sort of sheet material. They are also made exactly as real mast hoops are made. (In larger scales, small headed brass pins can be used to represent the rivets that hold steam-bent laminated hoops together.)

[DelF]

Bob

 

Perhaps mast hoops wasn’t the best example I could have cited for the technique - your’s is clearly better. Nevertheless it works. No Idea’s example is more appropriate. The method works well for most situations where you need to mill a circle or part 

thereof. 

[wefalck]

I think the discussion is diverging somewhat from the original topic.

 

In this building log below (no idea, why it shows a Christmas motif ...) I go through a wide variety of milling set-ups, albeit on different small mills.

 

[glbarlow]

4 hours ago, Bob Cleek said:

I take a mandrel ("stick")

I think I need pictures...

[glbarlow]

I’m looking to create a little more ornate mast cap at the base of the mast on the deck.

 

These all sound like nice ideas, but I’m not sure I follow the narrative description. 

[Bob Cleek]

1 hour ago, glbarlow said:

I think I need pictures...

Wikipedia is your friend. "A thousand words is worth a picture." https://en.wikipedia.org/wiki/Mandrel

 

There are lots of different types of mandrels. What I was talking about was simply a stick mounted between lathe centers, or even held vertically in a drill press chuck. The diameter of the stick would be the same as the inside diameter of the "ring" or hoop you wanted. Once the plane shavings are wrapped around the stick with glue and dry, they make tiny little laminated wood rings, like plywood. You spin the stick and sand the wrapped and glued shavings smooth, then cut them apart to the width you want using a jeweler's saw with the blade pressed against the spinning "stick" to cut a perfect circle around the glued shavings to separate the "rings" or hoops from the larger glued shavings rings on the stick. They you slide the rings off the stick. Make sense?

 

It was in response to a post about making mast hoops, A "mast cap" is the little "button" at the very top of a mast. A mast "boot" is a canvas or leather "skirt" lashed at the top around the mast and at the bottom around a trim ring at the deck which prevents water from running down the mast and leaking below. 

 

"A little more ornate mast cap at the base of the mast on the deck" would apparently refer to the trim ring over which the mast boot was lashed, so there wouldn't be a lot of point to an "ornate one."  Sometimes, however, the rings have a groove or recessed band around their circumference to permit the lashing to hold better.

 

If you want an easy way to make one, I'd suggest you take a suitably sized square block of wood with the grain running lengthwise and drill a hole the size of the hole you want in the middle of the ring into the middle of the block of wood. then, since you don't have a four jawed chuck, mount the block of wood on your three jawed chuck with the jaws inside the hole you've drilled in the block. Then turn the block to the outside diameter of the entire ring you want, and part off the thickness of the ring you want. If you want it "ornate," you can easily shape the outside edge of the ring however you want before parting it off the block/tube you've got mounted on your chuck. Drill the hole in the center deep enough and you can cut a number of perfectly matching rings from the "tube" you've made. This is entirely a lathe operation, but I think it's a lot faster and easier, and perhaps safer, than doing  the job with a mill and certainly requires less expensive tooling. 

 

"Anyone have an example or a source/reference I can look to?" "These all sound like nice ideas, but I’m not sure I follow the narrative description."  As with most things technical, nomenclature is important. Maritime nomenclature is further complicated by the different names for the same things in different languages, and even in different nations with the same language. (As with an automobile "trunk" and "hood" in American English which are called the "boot" and "bonnet" in British English.) Like any language, you have to spend time around people who speak it in order to learn it. It's true with machining, too. A "chuck" isn't a "holder" and "parting" is cutting off a machined piece from a larger hunk of metal spinning in a lathe. It's quite difficult to write instructions for how to make something when the writer and the reader are using different terms for what is being made and how it is being made! You will find your mill (and lathe, even more so) an amazingly handy machine once you learn how to use it properly.

 

There are many good instructional books and videos available.  Here are the public-domain U.S. Army training manuals for lathes and mills. I'd suggest you print them out and put them in a binder for reference. They're very handy and nobody teaches people without any prior knowledge how to do things better than the military.  Here's the manual on lathes:  https://www.americanmachinetools.com/how_to_use_a_lathe.htm  Here's the one on milling machines: https://www.americanmachinetools.com/how_to_use_a_milling_machine.htm  These address large machines, but the principles and procedures are the same for machines of any size.

 

Another wonderful resource are the YouTube videos by a fellow who calls himself "Tubalcain" or "Mr.Pete222." He's a retired metal shop teacher who has continued teaching on YouTube. His practical instruction is great and his presentation is entertaining. He's got hundreds of videos on everything under the sun to do with the old-time machinists' craft.

 

I'd offer a word of caution. Even though modelers work with small lathes and mills, these are two of the more dangerous machines in any shop. (The lathe is probably the most dangerous machine tool of all. Table saws account for more visits to the emergency room, but only because there are so many more of them in amateur hands.) If you aren't formally trained in machine shop operational safety, pay particular attention to the safety warnings in the written materials before trying anything on the machines. Rule number one, for drill presses, mills, and lathes: Never, ever, leave a chuck key in a chuck. Make it a habit to keep chuck keys in a separate place and when taken from that place, never let them leave your hand unless you are putting them back in their place. (A flying chuck key is a dangerous missile. ) Rule number two: Always turn the machine or work piece by hand an entire revolution before turning the power on to make sure all work is securely mounted and there are no clearance obstructions. Rule number three: Make sure you have no long sleeves, neck ties or chains, or jewelry of any kind on. (These can become caught up in moving machine parts with catastrophic consequences.) These aren't the sum total of safety rules for machine tools, but they are the ones I've was yelled at the most about before I learned them well! 

 

 

 

 

[allanyed]

Glenn,

I think there may be some misunderstanding of what you call a mast cap.  You mention it is on the deck.  The mast cap is at the top of the mast, and is usually rectangular with rounded corners, has a square hole for the lower mast top and a round hole for the lower part of the mast above it to pass through.   It sounds like you are looking to make a ring instead of a ring of wedges at the mast partners where the mast passes between the deck beams, or in POB, between bulkheads.   Can you post a sketch and confirm this is for your current build for Cheerful.  Below is a sketch showing the top of a mast and the mast cap.    If you are looking to make a ring,  a lathe might  be easier than using the milling machine. 

Allan

 

[wefalck]

I had the same feeling, that there is a confusion betweent the two items.

 

That ring of wedges really is a lathe job and not one for a milling machine.

[DelF]

Glenn

 

Making what you call mast caps with the mill worked very well for me, using the technique No Idea described. Here's a couple I made for Royal Caroline (not very good pictures, I'm afraid). I'll see if I can put some pictures together to illustrate the method more clearly.

 

Derek

 

[wefalck]

As a matter of fact, this ring of wedges would not normally be visible. It is waterproofed by a sleeve of painted/tarred canvas that is nailed to the mast and to the deck. It may also be fastened to the mast by a rope wound around it.

[glbarlow]

5 hours ago, allanyed said:

some misunderstanding

Yes, my lack of knowledge of nautical terms is a problem. I guess the proper term is trim ring at the base of the mast.  
 

I was just looking for a simple project for my mill, seems I chose the wrong thing.  I don’t have and don’t plan to get a lathe, especially not until I’m less exposed for my ignorance of mills, and obviously nautical terms.

 

Thanks everyone for your replies. I’ll figure something out for the trim ring. 

[DelF]

1 hour ago, DelF said:

I'll see if I can put some pictures together to illustrate the method more clearly.

Here goes. I'm making a 14mm wide ring for an 8mm mast.

 

It's an idea to make sure the dividing table and the mill are reasonably centered. I use two pointy things and eyeball them from different angles until they look lined up.

 

 

 

Once that's done you won't touch the Y axis again. Zero the X axis by holding the wheel fixed (so the table doesn't move) with your right hand whilst rotating the numbered dial until it is set at '0'.

 

 

Prepare a piece of dowel. It needs to be wide enough diameter for the sheet material to sit firmly on it, and long enough for it to be gripped well by the table. This piece is 10mm X 30mm. Also make sure the end is cut flat and square - not a problem on your Byrne's saw!

 

 

Next get your sheet wood. It doesn't matter what size and shape it is so long as you can get your required diameter out of it, and of course it needs to be thick enough. I'm using a small scrap of pear - it's too thick but that'll be sorted on the mill. Just stick the dowel to the sheet with a blob of ca.

 

 

Next, put the dowel in the table and lock the jaws. Remember to leave a gap between the sheet of pear and the jaws - you don't want to end up milling your table!

 

 

I'm using a 3mm cutter here. I'm going to cut the outside of the ring first, and because my mill is at the centre at I need to move it 8.5mm before I can start, because 8.5 = the radius of the ring (7mm) plus half the diameter of the cutter. That puts the cutter just outside the required circle. So, that's 8 1/2 turns of the wheel on the X axis. 

 

 

To start cutting, unlock the table (using the little black knob on the front), switch on the mill and lower the cutter. I find it best to take 2 or 3 cuts rather than trying to do the whole thickness in one go. Now that the table is unlocked you can just rotate it carefully by hand:

 

 

I normally use both hand to rotate the table evenly but I needed one for the camera for this shot.

 

You'll know when you're right through as the outside piece will spin free - at that point stop the machine and break the scrap off.

 

 

I didn't film the next bit, but all I did was raise the cutter, move it back in 3mm, and lower it again to thin the ring down to the thickness I wanted. 

 

The final milling operation is to cut the inner hole. If you've followed the measurements so far, you'll see that in order to get the 8mm hole the cutter has to move back in another 3mm. It's then just a case of milling down just like you did for the outside diameter. In this example I knew when I'd got through because the sawdust changed colour - I'd hit the dowel!

 

 

Btw - this work creates a lot of dust - I really should have sorted out my dust extraction before I started. Please don't follow my example! 

 

I wasn't going to bother for this sample piece, but as the ring was still stuck to the dowel I decided to chuck it in the lathe (a drill would work equally well) to sand a slightly rounded profile.

 

 

Finally, I parted it off in the Byrne's saw and here it is:

 

 

 

I can assure you, it took a lot longer to photograph and describe this than to actually do it. 

 

I hope this helps - it would certainly be a good exercise to help you get familiar with your new machine.

 

Derek 

[glbarlow]

9 minutes ago, DelF said:

hope this helps

This is great Derek and exactly what I was looking for. Just something to learn a bit about the mill and I will eventually need this ring for Cheerful. Thank you for taking the time to detail it out. 
 

I understand about the dust, I ripped three sheets of planking strips, about 40-50 last, night.  Lots of dust.

[wefalck]

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.

[stuglo]

Many thanks for the above lesson. I bought my Proxxon less than a year ago, but the learning curve (by myself) is slow. Other illustrated tips would be very welcome. Meanwhile, another problem. When using this head vertically, that is the piece is horizontal, even minimal pressure from the milling bit causes the piece to "dip" and results in an oval rather than a round effect. I could use a lathe but I have a very crude one and  milling a rotating part can be useful. I thought to support the free end but can't think how. Any help appreciated.

[wefalck]

Not sure, I understand correctly what the problem is - picture would be helpful, but it sounds, as if the workpiece has not been clamped down properly.

 

In general, lathe or mill, if the workpiece can flex or otherwise move, you will not get satisfactory results or it may even result in desaster.

[DelF]

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

[allanyed]

As to nautical terms, the learning curve has been a long one (at least for me) and still, some new  terms pop up now and again.  If you have a chance, read some of the contracts from the late 17th and early 18th centuries and there will be a slew of terms to deal with, if only because of the odd spellings compared to today. 

 

Keep in mind the ring around the mast is not a  cover or ring at all so maybe easier to make it the way it actually was, that is, a series of wedges to hold the mast tight to the partners.  Then again either way you go, it should be finished as Wefalck mentioned, with a canvas cover.  Thick grayish paint serves well to replicate the canvas so you would not see the seams of the wedges "wedged" together around the mast.  

 

The best reason to try to the mill though is to get in some practice!!   

 

Allan