This doesn't look right on here... but works!!!

[mdocod]

I just wanted to share this as it looks pretty silly on my small mill but it is surprisingly effective..... A 2" diameter 6 flute end mill. (yea, it's a cheapo, but it's not being used for any mission critical operations here)

I wanted to simplify and speed up one of my production steps for making battery adapters. Before I start cutting pockets and holes in a piece of a battery adapter, I always use the mill to size up the plastic parts to a nicer precision first. The saw I use to cut the plastic is very accurate for woodwork, but pretty pathetic when talking machining work.

Before, I was using a 3/4" 4 flute end mill in a 3/4" R8 collet and doing a neat dance of the X/Y table to navigate quickly over the surface of the part to true it up. This works reasonably well on smaller diameter adapters like 3xAA abreast stuff that uses just a 1.25" diameter rod, but on larger stuff, it gets more time consuming and tedious.

Long term thought here was to put an X-axis power feed on here for this operation, but that would only be worthwhile if the machine could handle a large cutter, so I figured I'd try the cutter first (it's cheaper) and I'll buy the power feed later if it worked.


I used it tonight to true up 1.25" diameter plastic rod (pass the mill right over it). DOC ranged from 0.15-0.40 for the most part. I did one where the over-size of the part was more substantial and had a chance to take a 0.075" DOC, as I recall I was running around 1200-1500RPM. The feed rate was basically as fast as I could turn the handle, Probably 24IPM give or take. No problem.

At first I was scared of the big cutter, now I simply respect it's amazing utility value and keep my fingers clear of it!


Eric

 

[precisionworks]

Nothing wrong with that

You'd also like an indexable end mill, and 2" is a common size. They usually have 3, 4, or 5 inserts. There are some on clearance for $24.65 that are very nice, although the largest one is smaller than 2":

http://www.wttool.com/category-exec/category_id/21054/nm/Tri_Dex_Indexable_End_Mills_APT_

http://www.michigandrill.com/catalog/view-mdc/173.pdf

 

[mdocod]

Hi Barry!

Wow, you're either up late (like me) or up early!

I have been considering several options like that. Like fly cutters and various "multi-"flute""cutters that involve replaceable little inserts. I'm betting that for anyone working in harder materials those tools work really well as the cutting inserts can be replaced at a fraction of the initial cost.

I was thinking keeping it simple. I think this end mill was only about $40 or so IIRC. I've yet to wear out or dull a single end mill that only touches plastic. They simply do not wear out in this application unless they are accidentally dropped. Provided I don't screw up, this is a one time deal for a lot of production work, and I have parts up to 1.75" in diameter that this can true up for me on a single pass on one axis. My experience has been that for more complicated operations (deep plunges and slot milling), spending more on better quality end mills provides better results (One of my smoothest cutters is a Niagara brand 17mm 2 flute).

When I first mounted this up in the machine I was really thinking that the massive size was going to equal a catastrophic event like flinging a part across the garage like a bullet. I started off with like 180RPM and very slow feed to see what was going to happen, and I was just amazed at how it made cuts without any vibration going through the machine. I played around with upping the feed rates and RPMs more and more until I realized that everything was running perfectly fine. For the cuts I need this mill to do, I'll probably never run into a problem even with the fastest feeds I can achieve by hand.


I'm just really excited about this overall.

Eric

 

[precisionworks]

you're either up late (like me) or up early!

The alarm goes off a 0430, giving me time for two cups of coffee and a quick check of the web before walking the dogs at 0500

the massive size was going to equal a catastrophic event like flinging a part across the garage like a bullet.

If you'd used the factory hard jaws, the likelihood would increase. With the custom bored soft jaws, that part is going nowhere:

FWIW, here's a neat looking shop built clamp for flat parts, called a see saw clamp:

Saw that on on the HMEM website http://www.homemodelenginemachinist.com/

 

[mdocod]

That's an interesting clamp setup there. I see some of the most creative work in this field. It's like artwork for garage nerds.

Speaking of part holding... Does anyone know if there is a 4 jaw 6" scroll chuck out there that would drop on the phase II without a major hassle?


Eric

 

[precisionworks]

4 jaw 6" scroll chuck out there that would drop on the phase II without a major hassle?

Any plain back chuck will work, but you'll have to machine an adapter plate. Here are some from Bison:

http://www.toolmex.com/new/products/index.cfm?cid=577_432_418_417&mc=N

You can also buy a "front mount" chuck that mounts directly on 3 or 6 slot rotary tables, or on a base plate when the table has 3/6 or 4/8 T-slots:

http://www.toolmex.com/new/products/index.cfm?cid=547_575_432_418_417&mc=Y