Capabilities: Is a 1 hp PM mill enough for 18-8 stainless steel? Or 2 hp?

[Gladiataar]

I traded for a used Jet knee mill quite a few years ago. Been happy with it. What I've found about limitations etc. : 3 hp I've never needed that much but don't really hog a lot. Far more time is spent optimizing setups and tooling changes than removing metal. Tooling and accessories will end up costing at least as much as the mill. Seems there is always something I'd like to have to make it easier. Any sort of variable speeding system is better than changing belt positions. Work envelope: I am far more likely to run out of Z-axis than anything else. Not in the size of the work but in the space used for work holding, boring head etc. A 3 axis DRO is so much easier to use than the dials. On a knee mill having a power feed on the knee has been worth it to me. I don't know about raising the head on a bench top.

Basic items you will want: decent vice, accurate drill chuck, caliper, micrometers just two to get started, boring head & bars, 115 pc. set of good drills, (I also really like my screw machine drills) a set of assorted HSS end mills, good edge finder, deburring tool, good files, set of HSS taps, a tap follower, set of parallels, chip & flux brushes, set of strap clamps, set of collets. Safety glasses always used! Way oil, cutting fluid/oil, gallon of WD-40 or =. Metal to machine. A metal lathe. A tooling cabinet. Note book. Charts for drill sizing, tapping, metric conversion. And you haven't even started down the rabbit hole.... Above all be safe, have fun.

The world of woodworking isn't much different. Especially when routing. About 90% of the time goes into set-up and fixturing, the remaining 10% goes into actually making a cut. Thanks for the comment regarding Z-axis clearance. The PM-833TV has about 17" of Z-travel and 20" of overall clearance. If you think that might end up getting too tight too often, please let me know.

I've already decided that any benchmill I buy will at least have Z-axis power simply because the head is so heavy. An X-axis motor might get added later on just to stabilize feed rates for the longer cuts and face milling. I would LOVE to have 3-axis DRO, but it's an $1100 option with PM. Rumor has it, that with a little elbow grease, a self-installed system can be had for about half that.

Thank you also for the detailed list of "accessories". Believe it or not, I already have a decent portion of this list due to the fact that I've been stumbling along for over 10 years using a lot metalwork tooling in my woodworking machines. I already have end mills, deburring tools, files, taps, cutting fluids, calipers, conversion charts, a metal cutting bandsaw, and several cobalt and carbide drill bit sets -- including machine length. What I will need to buy is a decent vise, a keyless drill chuck, an edge finder, and a quality set of collets. I might even have to invest in a set of parallels and precision blocks (???) Don't know, never used them before. Safety glasses are always the first thing to go on when entering my shop.

 

[projectnut]

If you're considering a knee mill and are pressed for space, you might want to look for a Burke Millrite. They're about 2/3 the size of the Bridgeport and very capable for their size. They seem to be popular with hobbyists because of their compact size and number of features.

As for moving machinery a little planning will go a long way. I've moved dozens of machines by myself using a drop deck trailer and some 1" rod as rollers. Drop deck trailers lower the deck to ground level for loading and unloading. To move the machine, you can lift one end with a prybar or "Johnson bar" just enough to slide a 1" diameter rod under it something like this.

Here's a link to some information and pictures on the Lathes UK website:

Page Title

 

[davidpbest]

I encourage you to read the attached. Hope this helps.

 

[Rich V]

Gladiataar

A lot of good advice so far, my 2 cents:
The first concern for choosing a mill is to be sure the work envelope is large enough to cover the parts you will make 90% of the time. Y and Z being the two most limited on a bench mill. You will hate machining if you are always trying to 'work around' the size limits of your mill.

Second is rigidity and available horse power.
Both of these will determine how much/fast you can remove metal. It may come as a surprise but some of the bench top mills are > to knee mills in rigidity. The small compact design of the bench top mill works in your favor here.
The classic Bridgeport design is not considered to be a very rigid design. It's design maximizes versatility but sacrifices rigidity.
Tool choice will also greatly influence metal removal rates. For example, choosing a regular end mill vs using a roughing end mill has a huge impact on removal rates. Same is true of face mills. Using different rake angles (90 vs 60 degrees) make a big difference in metal removal rates. There are lots of tricks in metal working that you will learn to maximize productivity. This site is a great place to ask questions and learn from the hive mind.

For the parts you mentioned in your first post a solid bench mill with 2HP motor will work for you assuming the working envelope is large enough.
Welcome to the club!

 

[rwm]

0.080 is a pretty large depth of cut for one pass on my machine. A lot of machines could do it but why do you have to do it in one pass? This will generate heat and be hard on the cutting edges. It might require flood coolant. You may decide this is better done in 2 passes. David's post has some great information.
Welcome!

 

[davidpbest]

@Gladiataar comments agree with my own sentiments. The Bridgeport-type mills offer tremendous flexibility (and powered quill downfeed for boring), but at a sacrifice in rigidity. They are also easier to tram than a square column benchtop mill, but realistically, once the benchtop column is trammed, it doesn't go out of alignment with heavy milling like the nod on the Bridgeport.

As far as stainless steel goes, the stuff is gummy but not excessively hard compared to something like 1018 steel. I machine 304 and 316 all the time, have done some very precise work in the stuff with both my RF-45 benchtop and my PM-935 baby Bridgeport, but you have to know what you're doing. Quality of tooling, precise and consistent feed rates, rigidity, and some form of chip evacuation are critical aspects of machining stainless on any type of machine. Additional HP is not the key to SS milling, technique is. You can see some tests I did on 304 here, and some examples of what my benchtop RF-45 was capable of here in 304 (read the descriptions that go with the still images). You might also have a look at some deep face milling operations in both aluminum and 304 using the PM-935 and Hass tooling at this link (watch the videos toward the end). Those videos will give you some idea of removal rate limitations in 304.

 

[skcncx]

Your point about the nod adjustment surprised me a bit. I did take note of the differences, but sort of assumed that was a one-time set-and-forget thing. Is the nod something that has to be adjusted frequently?

Can't say from experience, I've never done it and my 833TV mill will be my first... I think (for 99.999% milling operations) you want it in perfect alignment, there maybe a time you want it tilted (I just don't know when/why). My point was just to indicate that, there's really no adjustment per say to dial it in on the common square column benchtop mills. So, if it's not good enough, then it's a matter of making mods to the mill. Shim the connection from column to base, etc... I guess we can't have it all in a benchtop mill.

Rumor has it, that with a little elbow grease, a self-installed system can be had for about half that.

Take a look at the Easson, Aikron and Ditron, you can find DRO setups cheaper than $1000. I purchased a 4 axis DRO from Aikron, their A30 model with 4 magnetic scales for $850 (shipped to my door). Change that to 3 axis w/mag scales, take off $150. Go to glass scales, save even more.

There's a thread somewhere on here I posted the a discount for the AikronDro.com directly. It should still work, something like 5-10% off.

I can't comment on longevity of my Aikron, still on boxes, waiting for my equipment... but they are out in the wild and many like them... like many other brands.

Like so many other things, I never suggest buying just based on it's cheaper, every time I race to the bottom on price, I'm usually dissatisfied. Better not to even have it. Striking the quality/price balance is key. Picking up my 833TV mill this week... tooling, dro, accessories, don't even have a vise yet, I'm $2,500 in the whole, on top of the mill . Woodworking equipment seems really cheap now!

However, the ability to store a whole toolbox under a mill is not a minor point when comparing what needs to fit in an already crowded garage like mine. Good point and definitely a check for the bench style.

For me, my space and hobby requirements, this is a big plus for for me, even if it's not "ideal" for the milling machine, setup, weight, etc. I have a lot of woodworking equipment in a 24ft x 19ft shop and it works well because everything is on casters and I make effective use of every nook and cranny.

My lathe and mill, will be the first pieces that get a more permanent placement, even with bases on leveling casters

 

[davidpbest]

I posted a video a while back about how to check alignment and tram on a square column benchtop mill at the following link.

Feedback on this H-M forum thus far suggests that the 833 column will probably need to be trammed if you want to maintain tight tolerances of ±0.001. There are several posts here already on this topic. Once you watch the video link above, have a look a this thread:

DRO Aigner Thickness Stop Retrofit

The Aigner Thickness Stop system is an adjustable back-fence used on spindle shapers for trap-cutting components to final width in the process of adding a profile to one edge. it's used often for the machining of stiles and rails for doors as well as sash components for windows. The...

flic.kr

 

[davidpbest]

I also recommend reading the attached document which goes into some detail on adjusting tram on a square column mill. And the following video is also a good resource.

 

[B2]

I agree I spend much more time in design and set up than I do in actually cutting. Especially with CNC. So taking smaller cuts/pass is not a big issue.

I have little else to add to the comments, except. We all worry about size of cut, size of travel, etc. But depending upon your application, accuracy maybe be just as important in which case sometimes smaller is better. Example: If you want to engrave where you are moving very small tipped cutters over very short distances you may not want a very large machine which can make a 0.080 cut but could break off the tips of the engraving tool just due to its lack of precision at small steps. Also for these sorts of cutters much higher RPM would be needed.

Dave L.