Newbie- Fly Cutters

[Goldigger]

Hi,
Please can you help me out, id like to get a nice finish on delrin and ali.
Currently i make multiple passes with the largest endmill i have, but i get that mowed lawn look.
I've been looking at using a fly cutter to make the final surface cuts, please can somebody help me understand what i need to do to the tool steel that is clamped into the fly cutter?
Do i need to sharpen it, or grind an angle into it etc?
Or do i simply just bolt the square length into the fly cutter, and proceed to cut?

TIA

[roninB4]

You cannot expect to have a decent finish on the workpiece if you don't grind the cutter blank. It requires clearance on 3 sides (face, side, bottom) as well as having a radius blending 2 of those sides. You could do a search on the internet, read up on cutting tools in Machinery's Handbook (I did in 1979), observe/understand how an end mill cuts and do your homework. I'm not trying to be a jerk but this is really very basic information that any apprentice machinist should know by year 2. Perhaps if you had done the research and asked specific questions about tooling geometry it would be more gratifying to help you understand how/why things work. I've answered your questions in my first 2 sentences. Earn the right to what I've worked hard to learn and it's yours for free. If you show up asking for answers you weren't willing to try to answer yourself then it is perceived as just being lazy. I'm not trying to offend you, just wanting you to earn the right to receive what you ask for.

[arizonavideo]

Or you could buy a Face mill with the triangle inserts like this one.

1-1/2" 90

Replace the inserts with some nice ground ones and your good to go.

Here is some good cheep inserts.

10 New Made in USA TPG 322 C2 Carbide Inserts - eBay (item 200532457650 end time Nov-16-10 05:43:25 PST)

[Delw]

I think the first thing that should be done is to tram that head in on the mill, you just bought. I am betting its out .020-.030 easy, even if its out .002+ your gong to have problems unless you can do everythng in one pass.
second running a big dia off balanced fly cutter will add a ton of vibration into the machine again throwing it way off.

you didnt mention how thick or wide or long you work piece was nor did you mention how it was clamped, that can give you very bad results as well.due to part bending while cutting or being clamped.

as far as the tools that roninB4 mentioned thats teh way to do it but you can also use off the shelve tools and indexable inserts and endmills and get just as good results. I use the aluminum cutting ccmt 3 2.5 inserts for turning and milling on plastics and telflon. tool steel endmills very sharp ones work great for small flats on thick pcs.

most of your problem I am betting is due to set-up both machine and work piece/and or you work piece is very thin and its bending under load, even a light tool load will do that, that is why i am guessing roninB4 was critical on the proper tool for the job. as then you can skin a knats ass with the right tools.

Delw

[universalfab]

Originally Posted by arizonavideo Or you could buy a Face mill with the triangle inserts like this one. 1-1/2" 90 Replace the inserts with some nice ground ones and your good to go. Here is some good cheep inserts. 10 New Made in USA TPG 322 C2 Carbide Inserts - eBay (item 200532457650 end time Nov-16-10 05:43:25 PST)

There called shell mills, shell mills, fly cutters and these tools leave a beautiful finish. If you can use them, use them. If they give you problems, your doing something wrong. If you don't know anything about grinding a tool then learn or get a shell mill and use the preground carbide inserts.

[Delw]

his machine doesnt accept a r-8 collet. I think its a drill chuck with a mt-3 taper.
I wouldnt put anything very big in that machine. if you click his name you can view his posts and see what machine he is using.

[allrounder]

Hi. I took some beaut photos of one of the cutter bits I use for a finishing cut, but was not permitted to upload them - something about security tokens. Bit harder to describe....I use (only for finishing) the same cutter bits in the lathe as I do in the fly cutter in the milling machine, quarter inch square tool steel. Grind the end so it looks like the traditional-style American mailbox - rounded when looking from one direction and square when looking from the other. The tip is the top of the mailbox. Hold the tool steel in your hand with the curved surface uppermost and you are looking at a semicircle. Now rotate the tool so you are looking at the back of it. Both semicircles are the same size. You now need to grind the tool so that the back semicircle is smaller than the front one so that you have clearance most of the way around the semicircle. If you mark the centre of your two semicircles on each face, front and back, you are grinding down the diameter of the back one, but your new smaller semicircle must have the same original centre. But as the back semicircle reaches the sides of the tool you don't grind anything off. That is to say, the clearance is zero where it meets the straight sides, and probably most of a millimetre at the top. The amount of clearance you need depends on the radius around which you plan to rotate the bit. You need clearance to reduce friction where contact is not needed for cutting, and because you are swinging through a circle you need to grind off the cutter in a smaller radius than the radius of rotation to provide that clearance - you are making a circular cut into a flat surface. Then when you fit your cutter bit into your fly cutter, the front cutting surface if you imagine it extended, should pass through the centre of rotation. Your cutter rotation direction at the job surface should be towards the material moving towards it when the job is fed forward. In other words, the cutter speed and the job speed will add together to make the relative speed greater. Be sure to use a suitable cutting / cooling oil. If you have nothing better, CRC or RP7 are better than nothing and can be conveniently sprayed on the tip. Use a face shield and don't put any body parts where they can be hit if something breaks. Make shallow cuts only. You DID say FINISHING. I wouldn't use a fly cutter for deep cuts, though I DO use them for cutting gear and pinion teeth, with differently shaped bits, feeding gradually deeper, several cuts. Remember when grinding the clearance that the more metal you leave behind the cutting face, the stronger is the tool, and don't make any more clearance than necessary. Too little and you have to sharpen more frequently, as the friction will increase, causing heat and excess load/stress on the cutter, and too much causes weakening. Don't overheat the tool while grinding, you'll ruin the material.

[Goldigger]

Originally Posted by roninB4 You cannot expect to have a decent finish on the workpiece if you don't grind the cutter blank. It requires clearance on 3 sides (face, side, bottom) as well as having a radius blending 2 of those sides. You could do a search on the internet, read up on cutting tools in Machinery's Handbook (I did in 1979), observe/understand how an end mill cuts and do your homework. I'm not trying to be a jerk but this is really very basic information that any apprentice machinist should know by year 2. Perhaps if you had done the research and asked specific questions about tooling geometry it would be more gratifying to help you understand how/why things work. I've answered your questions in my first 2 sentences. Earn the right to what I've worked hard to learn and it's yours for free. If you show up asking for answers you weren't willing to try to answer yourself then it is perceived as just being lazy. I'm not trying to offend you, just wanting you to earn the right to receive what you ask for.

No offence taken..
I did have a scan on the internet but could not find the answers i was looking for...
Might i add, i went out and bought a mill 2 weeks ago. I've never in my life used one or did any metalwork during school.
This is a hugh learning experiance for me, and if people are willing to help me out along the way it will be much appreciated.
If you know a good resource for reading please recommend it..and then i can bug you less and not be so "Lazy"

The head is trammed too..
The size of the work piece will vary, but lets say for this project the biggest surface will be 100mm x 80mm

I have a Sieg SX2 500watt brushless motor http://www.axminster.co.uk/axminster...ll-prod809899/
3MT Drill chuck
3MT auto lock end mill holder http://www.axminster.co.uk/axminster...cks-prod23576/
Vertex 4" Rotary table HV4
Slitting arbor + saws
Plus various other bits

[roninB4]

Originally Posted by Goldigger No offence taken.. I did have a scan on the internet but could not find the answers i was looking for... Might i add, i went out and bought a mill 2 weeks ago. I've never in my life used one or did any metalwork during school. This is a hugh learning experiance for me, and if people are willing to help me out along the way it will be much appreciated. If you know a good resource for reading please recommend it..and then i can bug you less and not be so "Lazy" The head is trammed too.. The size of the work piece will vary, but lets say for this project the biggest surface will be 100mm x 80mm I have a Sieg SX2 500watt brushless motor Buy Axminster SIEG SX2 Mini Mill from Axminster, fast delivery for the UK 3MT Drill chuck 3MT auto lock end mill holder Buy Axminster Auto Locking Milling Chucks from Axminster, fast delivery for the UK Vertex 4" Rotary table HV4 Slitting arbor + saws Plus various other bits

-Glad to hear you aren't offended, a machine shop is not for the faint of heart. My suggestion for a learning resource would be Machinery's Handbook. I had NO background in the trades when I started, nobody in my family did either. I learned from grumpy old men and reading the handbook on my off hours. You may not understand everything you're reading but as long as it plants the seed of thought it will blossom. EVERYTHING you'll need to know is contained in that one book. The indexable insert cutters are ok, they're better suited for ferrous materials and a more rigid machine IMO as carbide is inferior to HSS in a smaller mill. If you're cutting aluminum or plastic it's hard to beat a square tool blank held in a fly cutter. For one thing, you can sharpen it yourself if the finish isn't quite right. It will also give you an insight into how cutting tools work when you change the geometry and/or the material you're cutting. You'll need to be careful of the depth of cut and your feed if you have one of the Chi-Wan mills as they often have plastic gears that drive the spindle. The impact of using a fly cutter can cause the plastic gear to explode and then you're dead in the water. Better to convert the mill to a pulley drive for 100$ (they're readily available on the internet). Run the mill with the locks partially engaged to minimize the shock and it will produce a better looking finish. Rough off the majority of the material with an end mill, use the fly cutter for the last .007 and you can produce a good looking surface finish. An end mill produces a more accurate surface but you asked for surface finish.

Like I wrote earlier, if you apply yourself to learning like most of us Olde Pharts did it will be more gratifying for the veterans to help a newbie like yourself. Just like we were newbies the grumpy old men helped out. That's the circular nature of passing the torch.......

Good luck and stop in often.

[Goldigger]

Originally Posted by roninB4 -Glad to hear you aren't offended, a machine shop is not for the faint of heart. My suggestion for a learning resource would be Machinery's Handbook. I had NO background in the trades when I started, nobody in my family did either. I learned from grumpy old men and reading the handbook on my off hours. You may not understand everything you're reading but as long as it plants the seed of thought it will blossom. EVERYTHING you'll need to know is contained in that one book. The indexable insert cutters are ok, they're better suited for ferrous materials and a more rigid machine IMO as carbide is inferior to HSS in a smaller mill. If you're cutting aluminum or plastic it's hard to beat a square tool blank held in a fly cutter. For one thing, you can sharpen it yourself if the finish isn't quite right. It will also give you an insight into how cutting tools work when you change the geometry and/or the material you're cutting. You'll need to be careful of the depth of cut and your feed if you have one of the Chi-Wan mills as they often have plastic gears that drive the spindle. The impact of using a fly cutter can cause the plastic gear to explode and then you're dead in the water. Better to convert the mill to a pulley drive for 100$ (they're readily available on the internet). Run the mill with the locks partially engaged to minimize the shock and it will produce a better looking finish. Rough off the majority of the material with an end mill, use the fly cutter for the last .007 and you can produce a good looking surface finish. An end mill produces a more accurate surface but you asked for surface finish. Like I wrote earlier, if you apply yourself to learning like most of us Olde Pharts did it will be more gratifying for the veterans to help a newbie like yourself. Just like we were newbies the grumpy old men helped out. That's the circular nature of passing the torch....... Good luck and stop in often.

Thanks for the info Ronin..
My Mill is the SX2 version of the Sieg X2, this comes with the 500watt brushless motor and it has the belt conversion... before I bought it I was aware of the X2 with the cheap plastic gears, which also comes with a 350 watt motor with brushes.
For the extra £60 its a no brainer to get the SX2.

I'll try and find the Machinery Handbook a bit cheaper than £83

Machinery's Handbook 28th Edition: Larger-Print Edition: Amazon.co.uk: Erik Oberg, Franklin Jones, Henry Ryffel, Christopher McCauley, Ricardo Heald: Books

Machinery's Handbook 28th Edition: Larger-Print Edition: Amazon.co.uk: Erik Oberg, Franklin Jones, Henry Ryffel, Christopher McCauley, Ricardo Heald: Books

[Barrie]

Hi, get a J & L catalogue or go online & search for (little?) black book, this is a small condensed version of the machinists handbook, it makes a zeus book like it's for beginners, it will give you most if not all of the info you will need, from f & sp's for endmills as well as drills, tool holder info, how to grind a drill (with free temp to do so), how to identify & grade carbide inserts, cost i think is about £12, i've been using one of these for years. it is a must for any machinest (i think).

[Goldigger]

Originally Posted by Barrie Hi, get a J & L catalogue or go online & search for (little?) black book, this is a small condensed version of the machinists handbook, it makes a zeus book like it's for beginners, it will give you most if not all of the info you will need, from f & sp's for endmills as well as drills, tool holder info, how to grind a drill (with free temp to do so), how to identify & grade carbide inserts, cost i think is about £12, i've been using one of these for years. it is a must for any machinest (i think).

Hi Barrie,
Are you refering to this door stop?


If so i already have one.. I also have a WNT catalogue..
Is this the little black book?


Cheers