Bushed

I have been continuing sporadic work on the beam engine with today being a relatively quick wee part: a bushing to hold the crank shaft onto the crank. Given that this part was about 1/”8 in diameter and 5/16″ long, it is one of the smallest things I have attempted.

My ML7 lathe was supplied with an excellent ER25 collet set that mounts directly on the lathe spindle. I thought it would be useful but I am still growing in appreciation of just how much. Holding onto the 1/4″ round brass bar I started with was no problem but niether was holding the finished 9/64″ barrel so I could turn off the remains of parting off. And, as is the special property of collets, it did so concentrically as far as I can tell. Which is just as well since I needed to finish reaming out the center hole from that side.

I find this especially exciting since this is getting into the range where I could turn bushing, bearings and the like for 1/4″ scale railroad models if I need to.

Drawer Deployment

Today all the recommended waiting periods for the assorted finishes on my newly built lathe storage drawers expired. This made it easy to find the motivation to get into the shop early. I find the prospect of doing a bit of tidying up when I have proper places to put things motivating. The demotivator is having to clean up and having no place for the stuff to go.

Here is a partial before shot of the shelf above the lathe. This has been the primary and only dedicated lathe stuff repository. It is nominally organized but piled deep enough that I can lose things I just set down.

I have a basic organizational scheme in mind in order from the top:

  • less frequently used small stuff I don’t put on the pending splash guard rack.
  • major accessories. The reason I went with 100 lb drawer slides.
  • lathe tooling, infrequently used accessories
  • rarely used metrology tools.

Not all was light and roses, however. In a mildly irritating oversight, my gauge block set case is about a half inch too long to fit in the rarely used measuring stuff. With foresight, it could have gone into the bottom of the metrology drawer. Bother.

Finally, the after shot of the shelf. I haven’t touched any of it but a bit of shuffling and it can be much more useful than it was. Instances of enraging small widget loss should be greatly reduced.

Offset Turning

As discussed in the last post, I need the beam engine cylinder head partially complete as part of my plan for drilling the various matching holes in the cylinder. This is a fairly straightforward turning of a 1/4″ projection on one end of a 5/8″ round bar. The fun part is that the projection is offset from the center of the bar by 3/32″. I thought it would be fun to show how I get the part set up in the lathe to achieve that.

Firstly, I blue and mark up the end of the length of 3/4″ brass bar. (It was actually .748″) Knowing the diameter of the bar, I measure the height of the bar sitting in a vee block on the surface plate. Subtracting half the diameter from that gives me the height of center.

I use the scriber on the end of the height gauge probe to scratch a line on the bar. I then rotate the bar and scratch a line twice more. If I haven’t messed up anything, all three lines should cross in the same place and that is the bar center. I then scratch a line 3/32 below center as perpendicular to one of the center lines as I can manage and center punch that point.

Now comes the magic part. I put the bar in the four jaw chuck and I set up my wiggler in the tail stock with the point in the center punched mark. I then adjust the chuck jaws until the pointer stops moving when I manually rotate the chuck. (Some people can just put an indicator on the bar and move the bar via chuck adjustment. I one try at that was an unqualified failure. This method works for me.)

Lastly, I set a dial indicator against the pointer and and refine things until it shows no movement.

Visually, success is demonstrated when I power up the lathe. The center mark should not be moving even as the actual bar gallops around. This is the ML7 going flat out at about 1100 RPM. It really is in focus! 🙂

Lastly, here is the finished product. Brass is like aluminum in that is comes out nice and shiny and looks really good.

I just need to drill the appropriate hole through the projection, and then I can re-chuck the bar in the 3-jaw chuck, turn it down to 5/8″ and part it off.

It’s A Lock

I started out learning 3D printing because I know there are things that are easier to make with that process as well as things that are almost impossible to make by other means at least by me. I did not expect to encounter an example of the latter case quite so soon but there it is.

The orange widget is a means of locking my Myford ML7 spindle in position so that I can unscrew whatever is on the end of the spindle. Previous methods involved wedging a bit of hardwood in there and prying. And then cleaning splinters out of the works. Versions of this better alternative turned up on the Myford Facebook group and someone more adept at CAD than I shared a file. My contribution was to add the hole for hanging on a peg.

One of the disadvantages of using the Toronto Public Library’s 3D printing machines is that only PLA is allowed. One of the advantages is that they have all the colours so I chose a safety orange for this item in the hopes of never forgetting and starting up the lathe with the lock in place.

DROp Dead Gorgeous

A fine old machine and her new cybernetic enhancement! After much (years) consideration, I decided to invest in a digital readout (DRO) for my Myford ML7 lathe. The DRO experience I have gained on my milling machine convinced me that increase in accuracy and precision would be worth it. (A DRO measures actual positions unaffected by backlash in the screws)

Next came a version of the build vs buy dilemma. Go with the UK vendor that sells machine specific kits for the ML7 or cobble together my own from components sourced on the internet. This sort of design challenge in an area where I am decidedly inexpert can cause me to decent into analysis paralysis for a long time. Maybe forever. Thus, I eventually decided to substitute money for stomach lining and invest in the machine specific kit from Machine DRO.

Upfront, I will say that I estimate that the kit cost roughly twice as much as buying individual components off the net would have. Given my historical propensity for underestimating things, the actual savings would be less than that when the job was finally complete. If, I should say. With the proven design and excellently written and illustrated instructions from M-DRO, I have a working installation 4 calendar days after the package arrived.

The kit is mostly bolt together using the included hardware including 1/4″ BSF hex studs that bolt into the existing taper attachment mounting holes on the back of the lathe bed. I challenge anyone to find those on this side of the Atlantic! The one notable exception and one that is optional but preferred, is installing the magnetic tape on the cross slide. This requires drilling and tapping two holes for mounting an extension block on the back of the slide and milling a 1.8mm slot in the bottom of the slide. My very first experience in working with cast iron!

I discovered that my milling machine had about of 1/4″ of room left when I set up to drill those holes.

The cross slide is way too big to hold in my milling vise so I had to clamp it directly to the milling table. This is another first and the also the first time I really used the clamping set that everybody buys when they get a mill.

The green painters tape is intended to keep debris off of the important sliding surfaces of the slide. Cast iron doesn’t produce chips but rather grey dust that is very abrasive. I ended up following along the milling passes holding my shop vac nozzle right up by the cutter. Who knew you needed dust collection for metal working?

All when according to plan and I have got the display mounted, at least temporarily on the backsplash. I am not entirely please with this but it will do for now. The backsplash is not as solid as it should be for this sort of purpose and I plan to eventually mount the display on the supplied mounting arm but I need to execute my under lathe cabinet plan first.

Final cleanup remaining is cable management and grounding the display. The read heads come with what I presume are standard length armoured cables that clearly would work for going all the way from one corner of a full sized mill or enormous industrial engine lathe. The kit came with copious hardware for this purpose which is much appreciated.

I am looking forward to learning how to use this thing and see what it can do to improve my results.

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.

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.