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View Full Version : What steps to take making a Fly Cutter ?



Sportandmiah
09-23-2009, 12:31 PM
I want to make a Fly Cutter and I am using a 3" long piece of cold rolled steel, with a little less than 1.5" diameter. I have a Sherline 4000 with a 3 jaw chuck and a live center. What order should I start making this? Here's my theory:

1. Drill center holes on both ends.
2. Chuck the piece and use a live center.
3. Turn shaft down to 1/2".
4. Reverse the piece and face and turn the base of the fly cutter to proper diam.

I am using the plan from here: http://bbs.homeshopmachinist.net/showthread.php?t=36349&highlight=fly+cutter

After that is done, I need suggestions on milling the 15 degree slant on the base of the cutter. I'll be using a HF mill.

Any and all suggestions welcome!

lynnl
09-23-2009, 01:32 PM
I'm sure others more talented than I will offer better advice for more accuracy, but I'd just grip the shank in a vise held in a vee-block, kicked over to 15 degrees, as close as I could measure with whatever available. I doubt that achieving exactly 15 deg is at all essential.

But you will, of course, need to do all your milling on that end all in one setup, i.e. face the end @ 15 deg, cut the slot for the tool bit, and cut the pocket for the clamping screws, all without loosening the vise. You probably knew that, but I thought it wouldn't hurt to mention, since it is easy sometimes to forget that sort of thing until too late. Lord knows I've done my share of those mistakes! :D

For drilling/tapping the clamping screw holes, I'd just lay it horizontally in the vise, again clamping it in a vee-block, and lay a scale on the flat to be drilled/tapped, and get that surface visually oriented perpendicular to the spindle. You could fiddle around with an indicator for (maybe) a little more accuracy, but I doubt that would make any difference in the end result.
I'd probably just scribe a line midway in that flat along which I'd center punch my marks to be picked up with a wiggler for the drill positions.

Carld
09-23-2009, 01:37 PM
You don't need to center drill it unless you just want to do it for the hell of it.

Chuck it up and turn one end down to the 1/2" shank as long as you want it.

Turn it around and face the large end off.

Put it in a vise held with the big end and flycut the face off to the desired angle. then mill the slot for the size cutter you want with one edge at the centerline.

Clamp it in the vise and drill the 3 or 4 threaded holes for the setscrews to hold the cutter in.

Done.

Sportandmiah
09-23-2009, 02:34 PM
You don't need to center drill it unless you just want to do it for the hell of it.

Chuck it up and turn one end down to the 1/2" shank as long as you want it.

Turn it around and face the large end off.

Put it in a vise held with the big end and flycut the face off to the desired angle. then mill the slot for the size cutter you want with one edge at the centerline.

Clamp it in the vise and drill the 3 or 4 threaded holes for the setscrews to hold the cutter in.

Done.

I'm just worried that the piece will come loose as there is a lot to turn to get down to 1/2 inch shank. I suppose I can reverse the jaws.

camdigger
09-23-2009, 03:27 PM
The lathe you're working on is small enough that the centre hole in the outboard end is a good idea. The centre on the inboard end is a waste of time, IMHO. If you can, turn the chuck jaws around to grip the outside of the part and mount the part in the chuck. Carefully centre drill the outboard end and mount the live centre in the tail stock. Turn the 1/2" shank to size for the length required.

Switch all back and mount the smaller OD to turn the larger OD for finish.

Best mounting for the mill would be to pinch the 1/2" shank and a vee block between the vise jaws tilted so as to mill the face. Personally, I'd use an end mill the same size as the intended tool bit to face off, cut the slot for the tool bit (with the leading edge of the toolbit on the centre of the flycutter), and cut a relief slot for all the cutter bit retaining screws.

Then remove from the mill lay out all the holes for the retaining screws and centre punch. Mount in the drill press vise with a piece of square stock in the tool bit slot of the work. Press the square stock down to the top of the vise jaws and clamp. Drill to tap drill size per the punch marks. cut a recess 1 thread pitch deep at the nominal OD of the retainer screws. USe the drill press to help align the tap and tap all the holes.

At least IIRC, that's how I did mine...

Carld
09-23-2009, 04:49 PM
If you can chuck that piece in the chuck it will not come out when your machining it for the shank. Your lathe doesn't have enough ass to throw it out.

The Artful Bodger
09-23-2009, 04:58 PM
I think you are wise to use a live centre to keep things under control. Every lathe, large or small, is plenty powerful enough to damage itself if something unexpected happens.

Sportandmiah
09-23-2009, 05:53 PM
Here's a pic of the piece chucked. I think I'll be using a live center. No point in risking a chunk that big slapping me in the face.

http://i160.photobucket.com/albums/t182/bigsport/cid__downsized_0923091731.jpg

camdigger
09-23-2009, 06:28 PM
It's all about perspective. In my 1440, I've often chucked up 2" MS round bar and merrily gone about making 0.200 deep cuts with 0.300 feed 3" out from the chuck and thought nothing of it. On my Taig (roughly the same size as your Sherline) I'd be a lot more conservative. Those jaws look to be gripping about 1/2" or so? If they work loose, the job could go very bad in a big hurry.

Having seen the stock you have, the original finish looks good enough, I'd be tempted to leave it as is and just turn the shank down. I might run a file on the exterior if pushed, but why??

Lew Hartswick
09-23-2009, 06:37 PM
That peice looks about twice as long as it need to be for a fly cutter.
We have two in the tool cabinet at school that probably aren't even
half that long. One is for a 5/16 bit the other for a 3/8 bit.
...lew...

lynnl
09-23-2009, 07:03 PM
Yep, no point wasting any stock length unnecessarily.

For a fly cutter, I'd thnk you should be able to get by just initially cutting the stock to length, plus maybe a few thou on each end for cleanup facing cuts.

Carld
09-23-2009, 08:05 PM
Yep, cut it in half, make two flycutters and you DON'T need a live center to keep it in the chuck. You can't take deep cuts with that little lathe with half the length that is in it now. If you try heavy cuts it would stall it out.

darryl
09-24-2009, 01:35 AM
I'd start by getting a different chunk of material. :) Cold rolled sure can warp on you. That may or may not be a factor with this project, but I'd pay some attention to that.

At any rate, that looks cool mounted in that sewing machine :)

Sportandmiah
09-24-2009, 02:05 AM
Thanks to all for the input.

I'm using the below pictured tools to turn. Can anyone help me, with pictures please, in regards on how to angle these when cutting? I have searched the internet for about a year and cannot find ANY information on how to properly use them.

http://i160.photobucket.com/albums/t182/bigsport/4801669-1.jpg

Astronowanabe
09-24-2009, 03:22 AM
there is information on the intertubes for how to turn...
you may need to translate information given for HSS tools to carbide inserts but it isnt that huge a difference.

Basicly the hieght of the top of the insert is the centerline of the work.
that leaves rotatation of the insert

1) if you just cut with the point you can make a deeper cut and leave a rougher finish.

2) if you cut more with an edge almost parallel to the work you can not take as deep a cut but will generally get a better surface (note the trailing edge of insert should clear the work)

3) in between those two extreams is well, inbetween.

So what often determines how the insert is set is what is the ending conditiion. do you run off the piece or is there a sholder? what shape is the shoulder? can you have the leading edge of the insert form the corrrect shape when you stop? what insert holder(tool) will hold the insert in the position you want it to end up in to form the shoulder?

you choose the tool that holds the insert the way you want
without it bumping into anything you do not want it to.

http://ix.cs.uoregon.edu/~tomc/images/turning_insert.jpg

A.K. Boomer
09-24-2009, 06:28 AM
Your lathe doesn't have enough ass to throw it out.



The amount of "ass" his lathe has is partially in direct comparison to what he's got mounted up in the chuck, sure it will take him a half minute to get it up to speed but if his motor windings make it through that then he has the potential to do some damage if the piece digs a little and disrupts its running of true,

In fact small machines have to be watched just as carefully in the form of momentum storage due to them having chucks with much less bite area even though there is a difference between the work piece itself providing the energies verses the stored energies of the chuck and machine having to go through the chuck jaws.


I agree your statement is correct in general and you made it before seeing how far out of proportion his pic is in overall length of the piece, also agree to cut the piece in half as I don't know why its so long for a flycutter.

What im wondering now is how many inside teeth of the chucks jaws are being grabbed by the scroll? I bet its something like 1 --- :eek:


Sportandmiah, You might consider building your flycutter like I built mine, to accept your lathe tooling -- it looks like your inserts have clearance from the mounts.

what this means is there's really no reason to build flycutters with major offsets -- at least I haven't ran into one yet,
My flycutter is 90 degree's, the insert provides the clearance -- this keeps the cutter more compact and closer to the spindle where it should be for rigidity.

http://i146.photobucket.com/albums/r249/AK_Boomer/DSC00200.jpg

Carld
09-24-2009, 10:35 AM
A.K., it's true if he runs to high an rpm he could have a dangerous situation. The speed is not as important as the DOC and feed rate when cutting a piece like he is going to do. He could run high rpm with reasonable DOC and feed but I don't recommend high speed for a job like that. The faster it's spinning the farther it flies if it jumps out.

The flat face on your cutter works fine if the cutter is projecting below the face. Most people use HSS or brazed carbide cutters in the flycutters and they must have some angle to the face so the rest of the tool clears the work. It would only have to be about 10 deg to work but better if it was 20 deg or so.

It's not really necessary to use carbide insert cutters for most jobs but if you run the flycutter as fast as I like to do carbide cutters are required. In fact I seldom use HSS cutters in my flycutters now.

The leading angle on the flycutter helps to reduce cutting loads and anything over 30 deg helps a lot. I use 45 deg most the time except on the insert holder I use.

Sportandmiah
09-24-2009, 12:38 PM
Excellent info, thank you all!

Metalmelter
09-24-2009, 01:45 PM
At the risk of hijacking the thread, and I don't wish to do that, I have a question regarding the safe mounting or holding down on the mill table of the cylinder head your looking to fly cut. I've been looking around the net all day so far and can't come across a good representation of that.

One interesting site was using something close to an 11" disc style fly cutter. So there are big ones out there. http://www.cdpautomachine.com/machine/shop.html

I figured I'd post the question here since the original poster might gain some insight as well as myself;)

cheers!

Carld
09-24-2009, 02:46 PM
Man, that is one nice all purpose mill there. You can see the fixtures he has to do the jobs and they have to be sturdy and precise and sometimes adjustable.

There is no iron clad way to hold heads or blocks to a mill table. Due to the irregular shape of heads and blocks there is no one way fits all. Many times you have to make a fixture that is universal of nature to hold the heads and it has to be very precise and solid for milling a head but not so much so for doing valve seats and guides. Holding most inline engines is easy but V engines pose a problem just as the heads.

You can make a flycutter like the one in the photo but be careful of the capacity of your mill. A fixed head mill as in the photo is best for boring and surfacing heads and blocks because you don't have to worry about getting it true to the table.

The Artful Bodger
09-24-2009, 05:26 PM
Getting back to the fly cutter project, I do not understand this desire to cut the stock in half! I though a real machinist would make as much of the part as possible and only part it off the stock when necessary to proceed further?

oldtiffie
09-24-2009, 06:33 PM
I don't know about a "real" machinist. I guess there must be if there are illusory machinists.

A "good" machinist does what he can with what he has in terms of material, machine/s, "time" and what-ever he is either told to do or just feels like doing that will get the job done.

There are any amounts of variations of fly-cutter holders/tools, but those that do the intended job are good tools.

A fly-cutter is an assembly of tool-holder and (cutting) tool.

Here is one I made to do a job. It is a bit of about 2" cold-rolled steel bar with a 20mm (~0.800") spigot on one end (for my largest ER-32 collet) and spare lathe tool-holder welded to it. It was just a "it looks (by "eye") like it is balanced and will cut well enough at a good speed" job.

And it did!!

It needs to be kept clear of when its running though as it could make quite a mess of the finger etc. of an unwary machinist.

It has a 5/16" square HSS tool-bit in it.

http://i200.photobucket.com/albums/aa294/oldtiffie/Fly-cutter/Fly-cutter4.jpg

It

camdigger
09-24-2009, 06:56 PM
Getting back to the fly cutter project, I do not understand this desire to cut the stock in half! I though a real machinist would make as much of the part as possible and only part it off the stock when necessary to proceed further?

That's what I'd do if the piece wasn't already the length required. Beats turning all that excess material into chips. I assumed the OP knew how much material he needed and was simply looking to profile the holder end after machining the held end. I have no idea as to how long a shank the O.P. has planned though.

Carld
09-25-2009, 12:40 AM
A real machinist would do it the fastest or best way he wanted to. You don't have to part everything nor do you have to saw everything.

I'm not real fond of parting to the center of an 1 1/2" dia. bar but I do it from time to time depending on the job. If I was starting the job I would probably saw it the length I want. If I was in the process of machining it and didn't want to take it out of the lathe I would part it off. If it were to short to saw I would part it.

To me there are no iron clad rules of what to do when, it all depends on the way I lay the work progression out.

camdigger
09-25-2009, 12:48 AM
A real machinist would do it the fastest or best way he wanted to. You don't have to part everything nor do you have to saw everything.

To me there are no iron clad rules of what to do when, it all depends on the way I lay the work progression out.

Another point to consider is what equipment is available. If you have a bandsaw you can tilt the vise on and cut a major part of the excess material off while you do something else like install the vise on the mill and dial it in, it would make little sense to take on a generally sphinter puckering exercise like parting off 1 1/2" material on a 4000 series Sherline....

A.K. Boomer
09-25-2009, 08:53 AM
The leading angle on the flycutter helps to reduce cutting loads and anything over 30 deg helps a lot. I use 45 deg most the time except on the insert holder I use.



The leading angle is independent from the flycutter itself and is subject to change depending on the toolings cutter angle - not just mounting angle -- this is the critical angle of attack --- 30 or 45 degree's just makes it handy for a square piece of HSS to be mounted into the cutter and has a pre-determined angle of attack so there's no need to clearance the hss cutter.

With a pre-clearanced carbide insert it make's this point moot, It also has great advantages over the old school 45 degree angle flycutter's -- no longer is your cutter "vertically challenged" (in being to tall) when you need the extra cutting swath and move the cutter out to maximum circumference --- not a good combo, you increase the swath and then move the cutter vertically away from the spindle at the same time, this plays hell with rigidity --- and I might add gives only HALF of the cutters adjustable swath capability for its size (due to the other half contributing to just making the cutter longer)
Not so with my 90 degree --- every single bit of circumference is utilized due to it being at 90 degree's --- So as far as the additional adjustable swath coverage I have twice as much as your 45 degree cutter.

If I want to use HSS I just get the rectangular bars instead of square, I then mount them up in the vise and clearance most of the bar to square except for the ends, then I put whatever angle I need for the job at hand.

But of course im not a machinist - just a mechanic.:p

Carld
09-25-2009, 09:49 AM
Ak, that would work too. It all depends on how you want to make the flycutter head. I will agree that the straight face on your flycutter would be more balanced than the angled face like most flycutters are but it hasn't really been a problem with the angled ones I have.

The only point I was and still am making is the angled head is easier to use standard brazed carbide and HSS if you don't want to use insert holders.

Not trying to say your way is not a good way. Both methods have their advantages.

Sportandmiah
09-28-2009, 01:48 AM
I ended up cutting it in half and turned the shaft to 1/2". Will post pictures tmrw.