Thinking of a mini lathe or milling machine?

[ednadolski]

Hi,

I'm thinking of investing in an entry-level hobby/benchtop milling machine or lathe, and I would like to solicit advice/guidance/opinions from the TRW knowledge base.   Primarily I am thinking of jobs like milling frames (mainly N scale, but also HO) and cutting wheel profiles and axle bores (i.e, P:87 stuff).   Would something like the MicroMark Unimat or the Proxxon mini mill be a reasonable starting point?  Or are there better options?

TIA,
Ed

[Jim Starbuck]

I had a bench top drill press already then added a Proxxon XY table for milling. While not particularly sophisticated especially in the Z axis it has allowed me to mill every N scale chassis I’ve wanted to do. I’ve seriously considered a Sherline mill but what I have works fine. I almost wish it didn’t so it would give me more reason to buy the Sherline.
A couple years ago I bought a Sherline model 4000 lathe. It seemed like a huge extravagance at the time but I absolutely love it. I use it quite frequently and it has allowed me to to do projects that I haven’t even thought of. Like building compound truck tower gears.
I almost bought a Chinese mini lathe from Harbor Freight and I’m glad I spent a little extra for better quality. The precision of the Sherline is outstanding as you can tell from the moment you switch it on. I would highly recommend the Sherline products because of the high quality. You’re only going to need to buy it once.
I would get the highest quality tools you can afford because using good tools makes the project so much more enjoyable.

[riogrande491]

Ed -

If you are coming to the A&O Santa ops next week we can chat about this in person. Until then, I strongly suggest avoiding either of the units you mention. I have owned a 17" Sherline lathe and 8-axis mill for over 20 years. They can produce precise work a lot better than I can. The variable-speed spindle motor is critical for avoiding tool chatter.

The Proxxon won't profile wheel treads. The Unimat doesn't have the rigidity and horsepower you would need to use a specially-ground form tool to turn the profiles. (Does anybody even sell such a tool for P:87?) I could never successfully turn a profile using XY hand wheels.

If I wanted to do wheel tread work I would probably go with a CNC lathe, although it might be possible using the Sherline lathe adjustable compound slide and a custom-ground HSS tool that has a tip radius that matches the wheel fillet. That said, one should gain experience using a manual machine before plunging into CNC.

Drills always drill oversize holes, so to get a precise axle hole one uses a slightly-undersize drill followed by a chucking reamer. In the photo below I'm reaming a 3mm hole in a part to build a new drive shaft for an early 1980's Overland C630.

It is commonly taught that end mills should not be held in a drill chuck, such as commonly found on a drill press. Most drill press chucks are held in place with a Morse taper that can wiggle loose from the side pressure of an end mill and quickly cause a dangerous situation. A hardened mill shank can spin in a chuck, whereas drill shanks are not as hard and grip better.

If you buy a machine (or two) you will use it for all manner of other jobs.

Sherline has a very complete set of accessories. It has been said that over time one will typically spend about half the original machine price for accessories. In my case, a lot more.

Bob

[rodsup9000]

Drills always drill oversize holes, so to get a precise axle hole one uses a slightly-undersize drill followed by a chucking reamer. In the photo below I'm reaming a 3mm hole in a part to build a new drive shaft for an early 1980's Overland C630.
Bob

 Bob, by doing it this way, you don't have the hole concentric to the OD. To get a concentric hole to the OD, you drill first, then use a micro boring bar to get ID within a few thousandth, and then ream. Or doing the way your doing, mount to mandrel of some sort, indicate the mandrel in, and turn OD.   

[peteski]

For some good recommendations see:
https://www.therailwire.net/forum/index.php?topic=40160.0
https://www.therailwire.net/forum/index.php?topic=45664.0
https://www.therailwire.net/forum/index.php?topic=50651.0
https://www.therailwire.net/forum/index.php?topic=54357.0

[riogrande491]

Rodney

Hole location was established to be concentric with a center drill prior to using a number drill. After reaming the hole, I turned the OD profile. The finished part was accurate and entirely satisfactory.

Bob

[wvgca]

i bought a aluminum framed cnc mill a few years ago ... was just over a hundred bucks,, and came with everything except a spoil board, and some cutters ... have a completed pic of it somewhere, just can't find it now ...
working area was about ten by ten inches, by maybe six inches high ..

[Ed Kapuscinski]

Somewhat relevant: one of my favorite Youtubers, Blondihacks.

https://www.youtube.com/c/Blondihacks

[ednadolski]

(Does anybody even sell such a tool for P:87?)

Hi Bob, yes, let’s chat…. Actually there is someone over onthe MRH working out a tool like that.  I’ve been thinking that it would be useful perhaps for re-profiling the code 88 wheels on the Tangent roller bearing trucks (since those have the rotating bearings)

Ed

[wvgca]

i know that carbide tools are available to do RP25 contours on rolling stock and loco drivers for HO stuff ..in one shot , various contours .. most common are the 110 and 88

[ednadolski]

i know that carbide tools are available to do RP25 contours on rolling stock and loco drivers for HO stuff ..in one shot , various contours .. most common are the 110 and 88

On what kind of milling machine or lathe is used fir doing that?

I also need to get good at removing factory wheels from their axles and pressing them back on true.

[wvgca]

they just looked like standard bits [with a carbide head] that you could insert into any quick change tool post ... i only bought the two that did my HO wheels, think they were about 20 apiece, and the replacement carbides were were just under 10