Milling Bit Questions and Vendor Recommendations

[Jay 1]

I'd like throw out a few questions I have about milling bits:

 

1) I'm looking for a US or Canadian vendor that sells milling bits that are reasonably priced and decent quality. Who do you recommend? Completely understand you get what you pay for, esp. when it comes to tools, so am looking for a decent balance between price and quality.

 

2) For our hobby, what size milling bits do you tend to use the most? Flat or round nose?

 

3) Which is the best way to go: 2- or 4-flute bits?

 

4) Is HSS the most versatile? I'm thinking at this point more of my milling will be with wood, but maybe some light metal work later on.

 

5) Would love to hear additional suggestions, recommendations, and ideas!

 

Right now I'm looking at using the bits with my Proxxon drill press x-y table (will use collets when milling), but will eventually step up to a proper mill--most likely a Sherline.

 

Thanks for your help and input!

 

Jay

[normanh]

I have a small amount of experience here, in respect of choice of cutters it really depends on what you are cutting as to what you really need, end mills or slot drills, consider the sizes and speeds as well, each have there advantages and costs. Usually the more cutting edges the better the finish but the cutter speeds and feed rates will be different.

 

Norman

[capnharv2]

Jay,

 

From my very limited experience . . .

 

From Chuck's blockmaking thread, he recommends Harvey Tools (no relation to me). I've ordered a couple of .04" dia HSS end mills, and I've been very happy with them. They ran about $25.00-$30.00 each. You can't order directly from Harvey Tools, but they will direct you to a local distributor.

 

Regarding HSS vs. Carbide, many places recommend staying with HSS unless you're milling harder materials (I use mine for wood and brass). I haven't tried Carbide yet, but I see no reason to pay more when I'm happy with what I'm using.

 

Hope that helps.

 

Thanks,

 

Harvey

Edited August 4, 2013 by capnharv2

[capnharv2]

Jay,

 

I apologize for not reading all your questions (I'm typing left handed, as I had surgery on my right hand Thursday).

 

2 Flute vs. 4 Flute? I've read 4 flute gives a smoother finish. I've used both and tend to agree. Of course, 4 flute mills are more expensive.

 

Regarding flat vs. round ends, if you're looking for a sharp corner or a long side cutting surface, I'd go with flat. Note that you can get flat end mills with corner radius as small as .01".

 

One last thing I learned the hard way (although  I suspect most know this already). If you're milling a slot, take out as much material as you can by plunge milling (like drilling into the material), then start on the end and cut your slot (like a router). I broke 2 of my end mills by trying to brute force my way thru the slot. Also, depending on the material, you will have to learn how much you can take off in each pass. Again, I learned that thru breaking some small bits. Note that as the end mill gets larger (in diameter), the less you have to worry about breaking the bit and the more you run up against the max power of you machine. And keep everything as stiff as possible-no big overhangs of the workpiece from the tool, expose the least tool shank as possible, and lock any axis on your table that you aren't using.

 

Believe me, I have a lot to learn!

 

Thanks,

 

Harvey

[Jay 1]

Norman & Harvey, many thanks for taking time out to answer my questions--very much appreciated!

 

Harvey, I especially appreciate your reply both for content and the effort it took you! I hope your hand surgery went well and that your healing is fast and complete!! I went through a right-hand surgery 4 months ago and totally can relate to how difficult doing somethings can be--like left handed typing or buttoning trousers or shirt buttons--while a hand is immobilized!! So thank you very much!

 

Harvey my use will be pretty similar to yours, so your info. is a great starting point for purchases. I'll google Harvey retailers (plus see about getting a Harvey catalog).

 

Jay

[capnharv2]

Jay,

 

This will take you to their website. You'll have to dig around a little to find all their end mills, but they have a huge selection of mills we can use.

 

 Click here for Harvey tools double ended corner rounding end mills.

 

Thanks,

 

Harvey

[Mahuna]

Hi Jay

 

I don't have a mill yet, but expect to get a Sherline Mill and Lathe setup in the next few months.  In anticipation, I've been reading "The Home Machinist's Handbook" by Doug Briney.  I highly recommend it - very simple and clear, and aimed at you and me - the beginning home machinists.  From what I've read, Harvey is right on with his advice.  Interestingly, I also just had hand surgery and the stitches are still in - the only difference from Harvey is that the surgery is on my left hand and I'm left handed.

 

To add some - HSS is what we should use - carbide cutters are more expensive, are brittle, and are mostly used for machining hard materials on automatic machines - not what we're doing.  The author also seems to recommend 4-flute cutters - smoother cuts, less vibrations, and work on most materials, although some can't be used for plunge cuts based on the flute configuration.

I've also been thinking about doing some 'milling' on a mini drill press with x-y table, but everything I've read seems to discourage it.  Drill presses are built for vertical stress, not the horizontal stress you get from milling.  If you have a full-size drill press you'd be better off using that for the milling type of cuts, using some kind of jig, instead of the mini drill press.  Another option for the full size drill press is to get an x-y table built for that size machine - I got one from Harbor Freight for less than $70.

 

The best advice I can give is to get the book I mentioned.  It's recommended by Sherline, even though the owner has published his own book.

 

Frank

[capnharv2]

Hi Frank,

 

I guess misery loves company

 

Yes, the Doug Briney book is a good intro. I have it and use it a lot.

 

There are a lot of lathe and mill web sites and YouTube videos too. A lot of them deal with materials and sizes we would never use. But, with some research, there probably are some good ones out there.

 

One site I've been looking at is the mini-mill web site

 

http://www.mini-lathe.com/Mini_mill/Main/mini-mill.htm

 

They have a lot of good information.

 

The Little Machine Shop has some good info too:

 

http://www.littlemachineshop.com/Info/getting_started.php

 

And by all means go to the Sherline web site:

 

http://www.sherline.com/

 

Look at the build logs from Danny Vadas and Ed Tosti, as well as some of Chuck Passaro's postings to get and idea of the tooling they use (I apologize to the dozens of other wonderful modelers out there who do beautiful work-it's just that Ed, Danny and Chuck were the first that came to mind).

 

Hopefully that will help.

 

Thanks,

 

Harvey

[wefalck]

I didn't read all the above answers in details, so apologies for any duplication.

 

HSS is tougher than carbide, meaning that it is more forgiving with the light machines we use. Carbide keeps the edge longer, particularly when milling wood. I think for doing a lot of woodwork, I would use carbide. It has to be run at higher rpm than HSS.

 

Depending on the price you are prepared to pay, you may not have much to chose between 3 or 4 flutes. Three flutes are usually cheaper. Three flutes also give more room to the swarf, so it is better with materials that make long bits. The more flutes the better the finish on steel usually.

 

Ball nose mills tend to be rather expensive and are only needed when you want a round corner. They are also used in CNC copy-milling, when free-form surfaces are to be shaped. Otherwise zylindrical mills are used.

 

If you want to do plunge milling, you need a bit that cuts over the middle, i.e. once cutting lip extends to the centre of the mill. Most cheaper bits are like this, but you have to sure.

 

When milling a slot, plunge-milling a series of holes is only a moderately good idea, as you may end up with jagged slot, unless you use a smaller diameter bit first. Don't attempt to mill a full-depth slot (depening on the final depth), but take out layers. The tangential forces may to much otherwise wor the bit and it will brake. You may have to experiment with rpm versus feed to get it right. In general, with our hobby machines, it is better to reduce feed, though this may be at the expense of surface finish.

 

Feel free to ask more specific questions when they arise. It is difficult to give recommendations, when you don't know the parameters of the machining job, e.g. material to be machined, diameter of slot to be milled/size of surface to be planed etc., type of machine available etc.

 

wefalck

[capnharv2]

Wefalck,

 

Thanks for your post. I read about plunge milling after I broke an end mill (trying to take too much off in one pass). I was able to clean up the sides of the slot in brass by using a mill smaller than the final width of the slot. I had some material that I could take off to clean up the slot.

I'll get some carbide end mills when I'm back to milling wood. About how much faster should a carbide bit turn than HSS?

 

Thanks,

 

Harvey

[wefalck]

In wood, it should in general run as fast as you can, giving you a better surface. The feed depends on the wood. In some woods you may need rather low feeds, or it will burn. Wood is a poor heat conductor and cutting generates a lot of heat. Some woods are very difficult to mill, more difficult than metal or plastics - but I am not really an expert on milling wood.

 

When milling metal with carbide, it is usually better to do this dry. Carbide is very susceptible to heat stress and unless you have one of those flooding-type coolant systems, you will not be able to produce a constant coolant stream. Applying a bit of coolant here and there will shock the carbide and may lead to breakage of the delicate cutting edges. You can apply say WD40 before the cut, but don't blow it on during cutting.

 

wefalck

[Jay 1]

Frank and Harvey, I guess the 3 of us are the bad hand bandits! Seriously, Frank I hope your surgery heals quickly as well--thank you for taking the time to reply with your offhand!

 

Wefalck, Frank, and Harvey, thank you for all this great information--very much appreciated! I'll be ordering Briney's book this evening. Your insights and knowledge have gotten me on the map. I did troll MSW for bits info., but didn't see a lot on the particulars about what's what when it comes to the bits. Wefalck, what you added about carbon bits is very helpful.

 

Given the cost of good bits, I want to invest in the right ones for the work we do. Nope, won't be doing any serious mill work with my press--if I run into something that will be a serious mill job, I'll wait until I have the right tool to do it safely and right!

 

Jay

[wefalck]

I am mainly using so-called 'disposable' short end-mills. They are a few Euro the piece. So if something goes wrong, one doesn't loose tens of Euros. I use the short ones, because our machines are not stiff enough to cope with long tool overhang.

 

For wood, 'secondhand' carbide mills are good enough. they come in sizes up to 3.2 mm (1/8"). They are often rather cheaply to be had and, therefore, also disposable.

 

Disposable mills make sense, because re-sharpening requires special equipment few people have. 

 

wefalck

[tkay11]

Could you name a European supplier of secondhand mills, Wefalck?

 

Tony

[wefalck]

Not really, when needed I get them from the electronic bay ...

 

wefalck

[tkay11]

Ah yes! Obvious answer! Thanks, Wefalk!

 

Tony

[Jay 1]

Wefalck, I'll use the source you suggest/use--it makes sense for bit sizes that are used a lot--much more economical!

 

Jay

[Pete38]

Guess I am lucky, where I work at a maintenance tech. I have a friend {tool and die tech} in our in house toolroom save any of the milling bits that they no longer use. Slightly worn for some of the steel applications but still of good use for wood.  Mostly 4 flute and some 3. anywhere from 1/8" up to 1/2" for size. Have enough now to probably do me for the next 10 years or so. Get a few carbide but not many. Mostly use HSS in the shop.