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What is the ideal setup for milling a long fluted rod?

Mr Steel

Plastic
Joined
May 22, 2022
I wish to mill some long fluted rods of a decorative nature (precision is therefore not so important a factor), but before I buy any accessories I thought I might ask about any alternative methods.

My original plan was to buy a dividing head, as it would allow a large number of flutes and come with a chuck and dead centre.

The stock I intend to mill is between 30 and 40 millimetres in diameter and 500 to 800 millimetres long stainless steel.

What would be best for this job?
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Would you wish to make straight flutes or spiral flutes?
Material steel or plastic?
To add to Bill D's good suggestion a 24 index, or a 36 index can make any number that can be divided into 24, or 36.

Even a low price bike sprocket might due


and with an index, you can retrace back into one of the original flutes.
 
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Mr Steel

Plastic
Joined
May 22, 2022
The ideal setup is to have the side that is away from cutting forces to be firmly/solidly supported so the material can not deflect awayby that pressure.
My idea was originally to use a dividing head and a dead centre on the other side, another idea I had was to make a few sets of holders for the rod sizes that I use.

But I was concerned about the rod bending in the middle as I will need to do rods up to 800mm long, that and dividing heads are rather expensive.

I plan to use horizontal milling on my universal mill.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Q: (But I was concerned about the rod bending in the middle as I will need to do rods up to 800mm long,)
Between centers with a long part, even ten inches long will be highly detrimental to tool /cutter live and part machining finishes.

Some sort of a steady might aid machining, perhaps a mill jack under the part.
Perhaps a stack-up gauge that pushes the part up.002 / .003 (if .002 is still in spec.).
 
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sfriedberg

Diamond
Joined
Oct 14, 2010
Location
Oregon, USA
You will definitely want some kind of backstop to resist the cutting forces and limit deflection. On a horizontal, this could be a V-block, a couple of adjustable parallels, or some machinist's jacks, depending on how you are holding and indexing the part. If the flutes cut away the parts that are normally in contact with the backstop, the backstop should be adjustable so when you cut about 1/2 the flutes you can take up additional slack. On a vertical mill, with the cutter rotating in a horizontal plane, the backstop could be an angle plate bolted to the table, brought up to contact the part on the opposite side from the cutter.
 

trevj

Titanium
Joined
May 17, 2005
Location
Interior British Columbia
Run an OD sized groove in to a piece of aluminum bar to use as the support, if your rod is too small to be contained against the gaps in the tee slots.

Use step clamps to follow behind the cutter that makes the grooves.

Have fun! It's not rocket surgery, or brain science!
 

dian

Titanium
Joined
Feb 22, 2010
Location
ch
alwys keeep track of where the cutting forces go and support stock in opposite direction. e.g you can climb mill and push the stock against a support.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
So a horizontal mill and a circular milling cutter, right? You definately need some support.

Find a used super spacer and footstock. Or a dividing head. Dividing head is overkill and most are not as rigid as a superspacer.

Arrange a vise, maybe two, to clamp the part in between the superspacer and footstock. You'll probably have to put blocks under the vise to get it high enough. Wood will work if it's all you have. You may deflect the shaft a bit but you said this is for looks only so you should be fine.

You've probably already got the vise so the indexing is all you really need.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
One simple device would be an index that you could make to fit the head or tail stock center with a Vice set mid-part to give a solid base and lock up to the part.

With a 36 index make 1, 2 ,3, 4 ,6, 12 and 36 precise indexes
48 tooth = 1,2.3,4,6,8,12,16,24,48
 
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The support could even be a length of dense hardwood, with a trough milled in it, bolted to the table.

Something i have done in the past is use a decent size 2-jaw chuck with V-jaw extension inserts to grip in the middle. Or to grip an end that can't be centered, when tapered grooves come to a point on the centerline.

A regular vise could be used, but a 2jaw chuck is self-centering.
So it is set and forget even if you want to do other size materials.
The V does not have to be 90deg. Mine was 120deg since the parts i was milling were 6 sided.

This also helps if your flutes go fully end-to-end. You will need an extension at the driving end to clear the cutter at the indexer nose. Even if the indexer is a gear. So, say, if you were using an extended expansion mandrel, it might have plenty of grip to index the part reliably, but not to resist the cutting forces. The chuck, if configured appropriately, will improve that significantly.

smt
 

Scottl

Diamond
Joined
Nov 3, 2013
Location
Eastern Massachusetts, USA
My idea was originally to use a dividing head and a dead centre on the other side, another idea I had was to make a few sets of holders for the rod sizes that I use.

But I was concerned about the rod bending in the middle as I will need to do rods up to 800mm long, that and dividing heads are rather expensive.

I plan to use horizontal milling on my universal mill.
Use a ball end mill to plough a rounded trough in a suitable length of aluminum. Put shims under it until it just touches the bottom of the rod without deflecting it upwards. Just clean any chips before rotating the rod for the next cut.
 

rrrgcy

Aluminum
Joined
Jun 5, 2013
Location
South Florida
My immediate thought that long for solidity is table it, c. 1910 re long shaft. Machine the tongue and blocking fixtures and t’s to fit. Pre-mark your flute lines on rod, fix to table, indicate and run that ball.
E1957-AAF-B53-A-45-D2-8-EFB-B6981-E44-A913.jpg
 
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guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
If you don't want to buy a spacer use a gear with appropriate number of teeth for index you want. Bore the gear and fix to shaft with setscrew. Use a piece of maybe .030 feeler gage stock in tangential orientation for stop finger, clamping it to machine table so it will catch a tooth. Hold the stock in vises.
 








 
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