70 replies to this topic

[S.O. Watt]

Also the Maximat is/was a pretty good lathe if you see one for sale.

A Shurline could get my vote if I were to upgrade from my 30 year old Unimat III(with all the bells and whistles) for my needs.

[Tim Neja]

Sherline is a great way to go! I've had one for over 30- years---and they have a "mill" conversion as well.  So buy two--one for a mill--the other for a lathe!!  Got all jobs covered then!!

[Rick]

Iffin' look around there are great deals out there. I picked one of these up for $250 with a 6 jaw Buck Chuck and collet chuck:

 

[Dennis David]

No room. Plus I think some people get too stuck on the gear aspect rather than just working it.

[SlotStox#53]

Wow Rick! That's quite a monster of a Lathe!   oh to have some room for one of those

[MarkH]

As a journeyman Toolmaker I can tell you that anytime you try to save money on machine tools the disappointment level is generally high. Almost everything we buy is made from the cheapest components and poorest manufacturing processes the customer base will tolerate. Happily this is not case with the majority of slot car stuff. So, almost everything else should be looked at as a starter kit. The better the kit, the less work it will take to make it right.

 

That said, even an average machine is better than no machine. It just will take extra care to make parts. If you are only making parts once in a while and only making one offs, even the less expensive machine might get you by.

Look for a heavy bed. Small parts require high spindle speeds and unless the 3 jaw chuck is balanced there will be vibrations transferred to the cutting tool resulting in poor finishes or hard to control diameters. A heavier bed will absorb vibrations better. Both the Little Machine Shop and Microlux “Appear” to have a slightly heavier bed.  I really like the .050” per rev on the handles of the Microlux and being able to re-set the dial to zero is important. My guess is the Little Machine Shop version may not have the .050” dial only because it is not mentioned. It is a whole lot easier to count off distance by 50s than 40s, just a preference.

 

Two other things that would be at the top of my list is a set of collets: 1) preferably a standard size like 5C (std lathe), R8 (Bridgeport) or the ER25 collet set at Micro-Mark. 2) A quick change tool post that utilizes a cam lock system is a must if you plan to machine more than one copy of a part. The tools can be setup and swapped out to perform the turning, facing, grooving / cut off or threading as needed quickly and accurately.

 

I really do not think I would get too caught up in the threading capability claims. While I would find it handy from time to time, most of what we use in slot car racing are very small threads. Threading in general is a skill requiring much practice and a lot of scrapped parts until you get good at it. A threading die makes more sense if making multiple parts. A holder can be made to put in the tailstock to ensure the threads are cut square to the center line.

[Duffy]

Good stuff, Mark, you said things that I hesitated to, afraid they'd scare guys off - but you said 'em in the right way!

 

A step further: a GOOD 5C collet set will be rated at .0008" runout, which some guys will say is still too much: setup and machining practice will help you with that, as well as a little secretiveness in your public announcements.

 

If you go with a machine with ".040 dial rotation" be advised: it might very well be a metric lead, meaning it's actually .03937" rotation - and that small difference will rapidly stack up. If you go that way, consider getting used to thinking metric and it'll be a lot easier on you.

 

I'll repeat the cautions about chucks: the scroll-type 3-jaw ones run out, and all big chucks are headaches for us. It's not only the wobble that sets up vibrations with 'em, either: the weakest point of a chuck is where it attaches to the spindle, and for most of these machines that's not a real finely-made joint set pretty far away from where your cutting is happening - so you're inviting chatter any time you take a good cut! Most of what we do is under 1" diameter anyway, so we can get away with the 5C collets (which you can get up to like 1.125" I think).

 

BUT none of this is really insurmountable, if you pick the best machine you can get with eyes wide open; you will learn your own techniques and methods that accomplish the best work possible with the machine you have.

 

Duf

[wbugenis]

I have two Sherline mills, and several more Sherline lathes.   All bought used  - mostly from ebay.

These machines are always available on ebay and with patience you can get a good deal.

 

They are made in the USA  and EVERY part is available from the manufacturer in California. No obsolete parts no matter how old or new the machine is.

Parts are always interchangeable - even between the lathe and mill

 

Great website - lots of good info:    http://www.sherline.com/

 

They will do everything any of the other small machines will do and just as well.

You cannot get away from the limits of a small machine.

 

Very importantly - collets are available in both metric and fractional sizes at reasonable price.

 

(Duffy, are you saying those USA made Hardinge collets will have  .0008 runout?   I am setting up my OD grinder - is that the best I can expect?)

 

More extensive range of tooling is available (again from the manufacturer with excellent service) than any other of the small machines

 

I have a couple of motor and headstock units mounted on a board -  so handy for when you just want to spin something up.

Again purchased reasonably from ebay.

 

I use these all the time and would not be without them.

 

I also have a 13 inch Clausing like the one Rick  pictured but it is up in the warehouse - won't fit in my basement and runs on three phase power

(I hate those phase converters) but I use the Sherlines ALL the time

[Duffy]

(Duffy, are you saying those USA made Hardinge collets will have  .0008 runout?   I am setting up my OD grinder - is that the best I can expect?)

 

I just E-chatted with Blanca at Hardinge, and she says standard concentricity, repeat, and runout tolerances are spec'd as .001" TIR with special order to .0002" - we did not talk "special" prices.

'Course, this is also dependent on the runout of the collet closure taper in the spindle particularly with super-accurate collets.

 

Best I could suggest is, have a good test indicator on an easy-to-use mag base and a small brass knocker close by. A couple taps just becomes second nature.

 

Duf

[MarkH]

Run out being TIR (Total Indicator Reading) means the center is off 1/2 of found run out. This is at the WORK HOLDING. True concentricity will be dictated by the quality of the spindle bearings in the machine. The run out only comes into play if you are turning a diameter relative to the diameter being held in the collet (Work Holding). If you need something closer than this, which will most likely be rare, put the part in the 3 jaw chuck and bump the jaws to get a zero TIR. If the spindle bearing are closer than .001" TIR just turn all your diameters in one setup and part it off. Clean up the parted face if needed.

 

In 5C collets you can get blank sizes that have three dowel pins in the slots to keep them from closing to create / cut any size you want AND match the concentricity of the machine spindle (theoretical zero TIR). That is the best you can hope for BUT the collet must be put back into the spindle nose in the same clocking orientation as does the collet nose into the spindle. Most of the time the 5C collet key is missing in the closure nose because a collet spins and damages it. Just take a small grinder and mark the collet, nose and spindle for clocking with a simple line.

 

You can "Blueprint" the three jaw chuck, kind of. Turn a disc of the average size diameter you will be holding with the three jaw chuck. Put this disc deep into the jaws, about 1/16" from the back edge, perpendicular to the bore and firmly tighten the jaws from all three chuck key positions (if there are indeed three). Then do a minimum cleanup bore to the jaws down to the disc. Open the jaws, remove the disc and tighten the jaws again an ID. Bore away the step in the back of the jaws left from the cleanup bore pass.

[Duffy]

...Yah, which is as good as the progressive graduation of the scroll plate in the chuck, so you may have repeat concentricity only at the diameter you turned! "It's always something..."

 

We're scaring the heck out of all the up&coming machinists, you know? But this is what we do all the time, and it gets practically unconscious the more we do it.

[wbugenis]

Not scaring anyone here Duffy

 

In another thread, Dan Miller responded to John:

 

"The average guy would also not take into account that the shaft need be straight. Real straight. To well under .0005" for low class armatures and better for a serious race arm. Armature shaft flexing, which takes place at high RPM, because of bent shafts, just hurts performance. As a footnote, triangular ground shafts can happen, when poor quality control takes place, during centerless grinding of hardened steel shafts. This effects results, when dynamic balancing an armature, in a negative way. But that is another story."

 

We are looking to repeatedly O.D grind the stacks of the armatures we make to get them as concentric as possible.  We are starting with  shafts about .0001 -.0003 runout

Looking for as little runout from the grinder as possible.

 

So I should give the collet a knock with a small brass hammer after the indicator tells me the high spot?

 

Sorry for hijacking the thread, John, but there is good info here

 

Bill

[havlicek]

 

 

We're scaring the heck out of all the up&coming machinists, you know?

 

 

I doubt it, but the thread is drifting a bit away from my original intent (just the facts m'am).  All this is interesting and informative, but really what I'm looking for is solid recommendations for a mini lathe.  So far, the Sherline seems like a good bet, but I'm also surprised to see some good stuff about the Harbor Freight-branded machine.

 

-john

[havlicek]

No worries Bill, I kind of said part of what you did   BTW, if that kind of runout is best you can do with that machine, it's suicide time!  (just kidding).

 

-john

[Duffy]

Yah well. Rocky Russo and I talked a lot about this motor stuff at one point, and basically the conclusion was that the level of the motor builder was more dependent on his own skill & only then on the equipment he used. Which can be kinda cruel-sounding, because the statistical proportion of tool & die makers out in the real world is about the same as it is in slots, but there it is.

In a very real sense, the numbers you can achieve are about the same as the numbers you're able to comprehend as being possible.

[John Streisguth]

There are a couple of used Sherlines on ebay, if you haven't already found them

[MarkH]

The Sherline looks pretty solid but does not appear to have Z axis power feed. Not a deal killer but it could make the difference if you want repeatable surface finishes. For my money, I would look at this as being a one time investment. How much the investment is should include all the tooling needed to make the machine functional. If you can afford it, my choice would be more towards the Micro or the Little Machine. There are plenty of good attachments/add ons that appeal to an aged Toolmaker. There is not that much price difference between the Sherline 4400, Micro or Little machine. But the Sherline also appears not to have a Compound Slide until you get to the $1100 package. Cutting angles would be difficult. So that would cause me to look harder at the other two.

 

-------------------------

As far as grinding the arms, my first choice would be to build a solid block with a "V" cut for the arm shaft to ride in. Indicate it in to zero / perpendicular to the axis the grinder will be approaching the work. Use screws on both ends to locate the shaft position on the center line of the "V" cuts. Cut clearance for the stacks and a drive belt(oring) that will apply tension into the Vs. Just like a com lathe, no mystery there. Then I would harden the block and NOT draw it back to keep it as hard as glass. Stone the Vs with a 1000 grit stone and then polish with felt bob. you will only have any runout that is ground into the shaft blank. With our Kart Racing Engines, that spin 17000 RPM, the cranks are split type and our fixture to get the center line alignment perfect is much the same as decribed.

[MarkH]

Duffy, well said. To me .001" is like missing the target by a foot when machining something "..that needs to be right". If I find it is off more than that I will keep working it until it is ok. I think for most everything in slots +/- .002" is more than enough except for things that spin real fast, wheel jigs or other precision gauges for setup. Then only +/- .00005" would be the target if it can be reached.

 

For a beginner machinist usually +/-.002" (Caliper measurements) is more than can be expected. Of course all this comes down to the ability to even measure these. A small surface plate, height gauge and .0001" indicator will get you started. Even learning to measure with a micrometer requires some practice.

[Rick]

Don't know about you gals, but when you start talking  .001 TIR usually the price would go up accordingly............

[MarkH]

Rick you hit it on the head. It would be interesting to see just how much TIR is built into these. Not sure about the Harbor Freight or Grizzly for any accuracy. The stuff we have bought from Grizzly is ok for some things. The small milling machine was only used to safety wire bolts in the end. The spindle bearings had bounce in them so basically just a nice drill press. It was sold off to buy a quality vise.

 

If I were to buy one small lathe, the Little Machine with the tooling package (#4287 @ $925) seems to get more of my attention. That said, If I could only have one machine it would be a mill. You can always mount something in the collet and put a lathe tool in the vise and turn parts down.Of course one would only have the Z axis travel, which will be pretty short, as the limiter for how long the piece can be.

 

These can be nit-picked to death. Before any cash left my hand I would get on their user forums and ask questions about accuracy and the experience level of those who respond. I sure wish I had not responded to this thread, now I am thinking about getting something for my empty work bench. Hmmmmm...........................

[Phil Hackett]

We used a Levin lathe for comm cutting when we were servicing arms back in the 90s. One sweet machine but it was an expensive piece. The price of WW or "D" sized collets are really high...

[Half Fast]

...

We're scaring the heck out of all the up&coming machinists, you know?

 

You sure are!

 

I still impressed by being able to cut metal with a Dremel!

 

Cheers

[wbugenis]

I'm afraid I caused some confusion on this thread.   I should not have intruded in John's question.

I think his  choice is between the Sherline or on of  the imported machines

 

I have a very old one of these:

 

http://www.crystalla...in_Grinders.htm

 

Which I am in the process of setting up for O.D grinding armatures with the least runout I can get 

It does not pertain to the question John raised 

Sorry for the intrusion - back to the cave for me.

[Phil Hackett]

Crystal Lake Grinders are good machines. Seen many get good bids at auctions...

[havlicek]

So, it seems we're down to:

-Sherline

-Little machine/Harbor Freight/Grizzly and others

-Micromark

 

...time to save my pennies (so I can turn them down into washers).

 

-john