Import (eBay) Shell Mill First Impressions

[G-ManBart]

I've been looking at decent shell mills/face mills for a while now and haven't taken the leap because I'm mostly trying to buy better stuff at a slower pace now...sort of the buy once, cry once concept and it wasn't near the top of my priority list. Still, I thought it would be handy to have one, and finally decided to try one of the cheap ones on eBay that gets shipped to you direct from China. It's for my Bridgeport 2J 2hp, so I went with a shell mill that's 2" in diameter and uses SEKT inserts (four inserts for this diameter). I also got the matching R8 arbor to go with it. For the arbor, shell mill and a box of 8 inserts it was roughly $70 including shipping. I figured if nothing else it would probably work for fast, rough, stock removal if not fine finish work.

Today I decided to give it a shot as I had a job where I needed to take a bunch off some aluminum blocks (was making a set of V-shaped pipe jaws with stepped teeth). The blocks were mounted in the vise together and milled as one. Considering the inserts are intended for steel I was pretty happy with the finish I got. It certainly feels really smooth when you run a finger over it. I was running around 1000rpm (random guess at what might work) and I will say that the chips looked good, and it sure makes a lot of them!

I'll link the the eBay listing for the shell mill if you want to take a look. There shipping was a bit hard to follow and I kept getting updates with different arrival times (a day earlier each time mostly), etc. It wound up taking about two weeks from order to delivery, which seemed pretty reasonable...it was some kind of UPS international service. I was a bit surprised when it arrived because the form they use on the outside for customs had different items listed and a total cost of about $50. At first I thought maybe the sent the wrong stuff, but it was correct, just a mismatched shipping form. I suspect they just use the same import form over and over and since it's under the typical $200 value the customs folks don't pay attention.

45° KM12 50-22 4Flute 50mm Face Milling Cutter Face Mill+10Pc SEKT1204AFN-FK | eBay

• Inserts type: SEKT1204（10pc）. KM12-50 22-4T indexable face milling cutter 4 Flute end mill for CNC LATHE. • Color: sliver. 1× KM12-50 22-4T.

www.ebay.com

Some pics of the assembled unit and the finish I got. There was a touch of aluminum buildup on the inserts, but not much and I probably removed .500" from the blocks, so a fairly decent amount. I'm definitely going to get some different inserts now that I have some faith it'll work reasonably well.

One disclaimer about the closeup of the finish...I deburred the edges and made a light pass over all sides when i realized I hadn't taken the surface finish picture. They actually looked a bit better before I ran them over the wheel (3M Scotch-Brite EXL) because they didn't have the straight lines showing. I'll try to remember to follow up with better pics and include some steel as well.

 

[mickri]

Loved your website about vises. I book marked it.

I have wanted a decent vise for awhile. I started with a HF vise that was awful. It got left behind when I moved last December. Where I used to live there were lots of farm auctions. Always had a vise or two up for auction. You could never get one because there was a guy who went to every auction and out bid everyone. Didn't matter what the vise was. He just kept bidding until he was the high bidder.

My current vise I got at a garage sale. It is a small vise with a 4" jaw on a swivel base. Don't recall the make. The seller didn't have a price on it. I offered $5. He came back and said that was too much money for the vise. Sold it to me for $2. It has served my needs so far. One of these days I will get a better vise.

 

[mksj]

You are getting some ridging from uneven cutter heights, in general you can use much higher RPM for carbide in aluminum,1000 RPM is too low unless you are taking very deep cuts. I run my 4" face mill at around 3000 RPM in aluminum and my 2" at 3500-4000 RPM. You can feed pretty aggressively for stock removal and then slow the feed for finish cut. You would probably benefit from some light air/coolant mist type system, I find it greatly reduces the build up on cutters as well as the regrinding of chips. Sharper ground edge polished carbide inserts should do a bit better, but there is still the accuracy of the pocket/insert which can cause ridging if not spot on. Below is my 4" face mill cutting 7075, the picture below was 4" blocks of 6061 that I surfaced using a Sandvik 2" face mill similar to yours. I bought both of these face mills off of eBay years ago, the 4" was around $150 and the other I purchased two together for around the same amount. Inserts can be expensive and you need to check that they are available, so starting out it is best to use more commonly available inserts. Many factors effect the final surface finish, so I would try more RPM and some air/coolant if available, also benefits from a power feed to get a consistent finish. The 7075 machines much nicer then 6061 and is less gummy, I prefer to use it for larger projects with a lot of machining.

 

[MrWhoopee]

I bought the same cutter off Aliexpress. Been using it for roughing 4140HT and lathe tool shanks, .060 DOC @160 rpm. Doesn't leave a very good finish like that, but I don't expect it. Really chews the metal off and the inserts are holding up amazingly.

 

[erikmannie]

I am always amazed how affordable the Chinese products are, especially considering that it included 10 inserts!

 

[G-ManBart]

Loved your website about vises. I book marked it.

I have wanted a decent vise for awhile. I started with a HF vise that was awful. It got left behind when I moved last December. Where I used to live there were lots of farm auctions. Always had a vise or two up for auction. You could never get one because there was a guy who went to every auction and out bid everyone. Didn't matter what the vise was. He just kept bidding until he was the high bidder.

My current vise I got at a garage sale. It is a small vise with a 4" jaw on a swivel base. Don't recall the make. The seller didn't have a price on it. I offered $5. He came back and said that was too much money for the vise. Sold it to me for $2. It has served my needs so far. One of these days I will get a better vise.

Thanks! For a while around here I was the guy buying all the vises at farm auctions, so I know how that goes. I'm not a collector, but I had fun restoring them and giving them new homes. I've only got a couple left, but kept one big one (Wilton C3 that weighs 175lbs) and a couple in the 3-5" jaw width range. I still have a cheapie with a crack repair on my welding bench as a beater...figure I'm not worried what happens to it!

 

[G-ManBart]

You are getting some ridging from uneven cutter heights, in general you can use much higher RPM for carbide in aluminum,1000 RPM is too low unless you are taking very deep cuts. I run my 4" face mill at around 3000 RPM in aluminum and my 2" at 3500-4000 RPM.

If there is ridging, it's certainly nothing I can feel when I run my finger over it. That picture is really zoomed in (those blocks are 1 x 2.5" and take up almost all of my screen, so extreme closeup) and with the naked eye the swirls look pretty much like what I see in your photos. Running the pieces over a wheel first made it them look duller and may have exaggerated how they look.

I'm going to take more pictures and play around with speeds and add coolant next time. I varied the DOC from .015 up to .045 in .005 increments to see what happened and stayed at the same 1000 rpm. I figured I would just change one variable at a time since it was a small project. I didn't want to change two things and not know which made a difference