Show me your flycutters...

[LKeithR]

Flycutters. What works? What doesn't. I want to buy--or build--a decent flycutter for my mill but there are so many different styles out there I'm not sure which way to go. I'd like to have something capable of working out to about a 6" width, preferably with insert tooling as I don't really have the patience to spend a lot of time grinding HSS. I wouldn't rule HSS out but it's not my first choice...

[dp]

Both of these use HSS rounds for cutters. I don't use a center drill!


Not sure who provided this but I've used the design and it does a clean job





Here's one that Frank Ford made:
http://www.frets.com/HomeShopTech/Pr...flycutter.html

[drmico60]

Flycutters. What works? What doesn't. I want to buy--or build--a decent flycutter for my mill but there are so many different styles out there I'm not sure which way to go. I'd like to have something capable of working out to about a 6" width, preferably with insert tooling as I don't really have the patience to spend a lot of time grinding HSS. I wouldn't rule HSS out but it's not my first choice...

You might like to consider tangential tool geometry for your flycutters. I have found that this geometry give a smoother finish and gives a greater depth of cut. More details are here:
http://mikesworkshop.weebly.com/tang...flycutter.html
Mike

[Jaakko Fagerlund]

Just make a slot to your holder so that one side of the goes through the center and use regular lathe tools with indexable inserts, like DNMG, WNMG or what ever you want. Attach with screws

[Mcgyver]

Dennis, I don't think that geometry is correct. I think what you have as back rake is the rake and what you have as rake isn't neccessary. These do not work like lathe knife tools, they cut on the end not the side (you're not plunging, right?)....a lathe knife tool will work, but not as well

[Carld]

[dp]

Dennis, I don't think that geometry is correct. I think what you have as back rake is the rake and what you have as rake isn't neccessary. These do not work like lathe knife tools, they cut on the end not the side (you're not plunging, right?)....a lathe knife tool will work, but not as well

I'll attach the cutter to a holder and take a picture. Because of the rotation of 90º I think it might be hard to follow all the angles. The angles are not to scale which is another problem. I also have a 1/4 rounded cutter that is a similar principle. I think I saw one a few days ago on the HMEM project logs forum. I'll dig it out, too. I actually don't care for that style fly cutter holder so don't use them often.

Edit: Hang it all, I can't find the cutter but I located the mockup I made for testing my grinding jig. I've discovered it is much easier to grind 1018 than HSS when you're not sure of the outcome

Here's the mockup - a spittin' image of the missing HSS cutter hovering over some crufty CRS. Were I to try cutting into it with that 1018 mockup I fear the scale on the bar will wear it flat in short order.

Anyway this shows the arrangement of the faces of the cutter to the work. Looks like I also flipped the image in all the cropping and sizing. NGDGUP! Fixed. Something odd about iPhone images.

This is nothing more than a left-hand roughing cutter from the oldie days of lathe cutter designs.

[willmac]

I think that within reason, more mass is better in a fly cutter. This is one that I have used a lot, mostly for cast iron. The fly cutter body is mounted on a 40 taper boring head shank. It can take 2 cutters so that you can get a rough and finish cut in one pass. I don't use it that way so often, because although it is a theoretically good idea, it is a bit of a fiddle to set up right. The compound angle of the tool bit hole seems to work OK. I typically rotate the tool bit a little to get the best surface finish, more by trial and error than anything scientific. This gives a slight 'shear' action to the cut. The significant mass of this tool does tend to make the cutting action smoother, but it is still a bit hard on the spindle gearbox on my mill. I have a nice face mill now and have tended to use that more than the fly cutter recently. It is much kinder to the mill but it doesn't get any better finish than the fly cutter.

[elf]

Flycutters. What works? What doesn't. I want to buy--or build--a decent flycutter for my mill but there are so many different styles out there I'm not sure which way to go. I'd like to have something capable of working out to about a 6" width, preferably with insert tooling as I don't really have the patience to spend a lot of time grinding HSS. I wouldn't rule HSS out but it's not my first choice...

Is this what you're trying to cut? They're pretty soft, so you should be able to use any kind of metal

[A.K. Boomer]

Flycutters are pretty simple business,,,
I built mine 90 degree's for all kinds of reasons including being more ridged and also getting the full swath of my cutter and adjustment - I really have no idea why flycutters are built with huge angles - I think it's an old school paranoia about clearance for the cutter - as U can see in the pic below - I think I only have about .018" of clearance and it does just fine, used it just yesterday to mill a cylinder head

I guess if your building one to use a high speed steel cutter then it would be better to have a small angle otherwise you will need to modify the hss cutter, but you still don't need something with a 45 degree angle -- that's throwing half of your cutters adjustment swath away...



The only thing else I have to add is make sure your set screws are on the right side --- you don't want the loading pressure of the cutter against the screws - you want it against the flycutter itself...