Roller Gauges: Design Meets Reality

Two Proto:48 Roller Gauges

When I got to actually laying out the dimensions on the first gauge (ie, marks in big Sharpie with dial calipers, I belatedly realized that the .036 flange width on the ends would be very delicate and vulnerable to damage if one, er, hypothetically dropped one on a concrete floor. Which is why my previous efforts had .100 rims rather than aspire to fit right in the frog of turnouts. I opted to repeat that choice for durability’s sake.

Being an aspiring novice hobby machinist, there are things I know need improving in the execution of these parts. Measuring those small gaps with dial calipers isn’t the most precise method but all I have that works. The finish isn’t as smooth as it should be which I know how to fix but will require developing my tool bit sharpening skills. There are probably things I don’t know that should be improved, too.

Anyway, parts done and sent off into the pre-Christmas postal maelstrom.

Milling About

I haven’t been doing much directly on Comstock Road recently but I have not been entirely idle. Having acquired the lathe and producing some roller gauges, I had not done much with it since. I recently resolved to get a better grip on the lathe’s capabilities and improve my rudimentary machining skills.

The lathe came with a vertical milling slide that bolts to the cross-slide and can be a substitute for an actual mill, up to a point. Being sparsely supplied with t-nuts for attaching things to either slide, I set out to mill down some that came as part of a machinist’s clamping set. (The Myford t-slots are 3/8″ wide but the cross of the T is both thinner and narrower than standard and the vertical part of the T is shorter.

Here is what the milling slide setup looks like:

Getting to that point definitely involved some learning opportunities:

  • I figured out how to read the change gear chart and reduced the feed rate which involved removing and reinstalling some things where washers at the wrong place caused gears to interfere with covers.
  • Got the spindle drip oilers adjusted, more or less. Cleaned grease out of various oil fittings and hopefully got things properly oiled.
  • Filed down a t-bolt to get it to fit so I would have enough to secure both milling slide and vise.
  • Ground the vise mounting lugs out with a rotary tool to get said bolts to fit.
  • Figured out how to square up the slide and the vise.
  • Worked out how to use a dial indicator to measure travel on the carriage.
  • Learned to not bump said indicator in the middle of an operation…
  • Learned that locking the carriage before doing a milling pass was not optional!
  • Much learning about work holding.

I had two exciting failures in workholding resulting in a missing chunk from the top corner of a nut in one case and, in the other case, jamming the whole spindle. Neither was catastrophic.

Here is one of the resulting slimmed down nuts, ready to hold something down. The first something is likely to be a carriage stop since using a dial indicator to measure carriage travel is a bit insecure. I intend to eventually work my way up to some sort of small live steam engine.

0.35mm Off the Middle

The lead screw kit I recently acquired for the traverser included an 8mmx6mm flexible coupler for joining 8mm lead screw to a stepper motor. I had hoped that the specs meant 6.35″ aka 1/4″ but no such luck. My choices where either to go and buy an 8×6.35 coupler from my local robotics store (yeah, being able to say that is kind of cheating) or drill out the 6mm hole to take a 1/4″ shaft. The couplers are less than $10CDN so it isn’t that big a deal but I decided that drilling with my lathe was a capability I needed to exercise.

Of course, I didn’t have an appropriate set of drill bits so out I went to the local big box store. $50 later, I was ready to save $10. Payback on the lathe is going to take a long time at this rate. 🙂 Seriously, though, I think a boring capability (for bigger holes) is the only thing I still need to acquire. From hereon in, it should be all down hill.

The actual setup and operation was refreshingly simple, I just removed the set screws from the coupler, chucked it in the self-centering three jaw chuck, chucked the bit in the Jacobs chuck in the tail stock, adjusted for distance and drilled away. It took no more than five minutes.

If this was all I ever needed to do, the lathe would obviously be overkill. On the other hand, having one available makes this sort of thing dead easy and it gives me satisfaction to get useful things done with it.

Here is the setup with the work just done:upsized

And here is the coupler installed on the stepper shaft.quarterinched

That’ll Do

gaugemk2

Second version of the roller gauge with the relieved center section. Second attempt at this design. Pro Tip: don’t part off the piece until you check that the rail actually fits in the slot.

I am getting somewhat faster at this. It took about 45 minutes for me to make it with all the measuring, re-measuring, calculating, and most especially, changing tools. The lathe came with a quick change tool post but only one regular tool holder. I have ordered some more holders and will probably hold off on the next one until the order gets here.

I have been plunking along on the tieplate infill and have gotten the traverser down to the fine adjustment stage. Time to get rolling on that.

Roller Gauge Mk1

Various people have asked me what the lathe is for. It is, of course, for many things (I have a hammer and I am looking for nails) but the first on the list is some Proto:48 roller gauges. The project was chosen since it is both straight forward machining and because I have an immediate use for them.

Straight forward is not the same as trivial and I am learning as I go. Twenty years is not the recommended period between class and practice. I am also learning things like where to go to get a replacement for the headstock v-belt and where to go to buy small quantities of metal.

Here is a piece of .5″ round brass rod chucked in a collet and ready for attempt number two. lathesetup

And here is the result of attempt number one. Despite a collection of learning moments, the end result is actually functional much to my surprise. The next version will have reliefs cut to clear other rails so I can use them in turnouts. The advantage of this type of gauge over the three point ones I have is that they don’t obscure a lot of the rails.gaugemk1

That’s Better

Fear not, this is not suddenly turning into a amateur machinist blog. That said, here is a shot of the new tool up on its stand and put back together. Various setup, maintenance and operation questions still to be resolved but I hope to get at those roller gauges soon.ml7.jpg

Heavy Metal!

When Trevor told me that he was acquiring a Sherline lathe, I promptly suggested that roller gauges would be an excellent starter project and that Proto:48 would be an excellent choice of gauge. Being the excellent friend that he is, Trevor suggested that I get my own lathe and make my gauges myself. There I sat until I overheard another friend discussing the sale of a lathe in the pub after a show. Being a bit late to the fair, I ended up on the waiting list in case the potential buyer decided to pass.

Here is my newest modelling tool: a Myford ML7 only a year older than I am sitting in the back of the modeller transportation unit.ml7woot

This is looking at the back with the motor detached and the tailstock removed to minimize the weight. I am fortunate to have the opportunity and means to take this machine into my keeping for a time. And also to have a couple of teenagers to help me get it into the basement. Getting things put back together will be an education.