the Papertrail – Page 47

My CNC mill

Posted on 2013/08/20 by kpmartin Posted in Basement Workshop — 4 Comments ↓

This Sherline 2000 mill is one of the main tools I use for making repair parts for printing machinery. Since I bought it I have retrofitted it with Sherline’s CNC conversion kit, using a home-made stepper driver (the gray box on the intermediate shelf) and a refurbished computer (bottom shelf) running Windows XP and Mach3. The monitor is mounted above the mill on a post, there is a shelf for the keyboard and mouse, and the whole thing is self-contained on a rolling stand.

People familiar with the Sherline mills may notice that this one does not have the “8-way” column that is normally part of the model 2000 mill. Since I bought the mill, I also purchased the single-piece rigid column that is standard on other Sherline mills and fitted it to my mill, and now I only use the 8-way column when I need its reach or range of adjustment. I had found that the adjustments on the 8-way column had a habit of drifting at the most inopportune of times.

The guts of the stepper driver box are three 5-Ampere stepper driver board purchased in kit form from Dan Mauch (but they are not longer available).

There are two power bars attached to the table, with one plugged into the other. The second one has all the CNC parts (computer, monitor, stepper driver) plugged into it, while the mill head motor and any added lights are plugged into the first one.

The keyboard is one of the silicone flexible keyboards, to prevent problems from flying metal chips. Unfortunately I found that these keyboards had a very short lifespan and terrible key feel, so for now I have a regular keyboard wrapped loosely in plastic food wrap film. Someday I will splurge on a proper commercial-duty sealed keyboard.

Bookplates for the Papertrail library

Posted on 2013/08/13 by kpmartin Posted in Kevin, Printing, Type Casting, Type Setting — No Comments ↓

In addition to about 97 books and other documents related to the Monotype machines, we also have a library of over 100 books related to papermaking, bookbinding, paper decorating, origami, typography, and printing. The Monotype books were coming with me the the upcoming Monotype University and I wanted to label them, so I decided it was time to make some bookplates.

I managed to cast some type, set it, print the bookplates, clean the press, and put away the type all in one afternoon (although I fired up the heater on the caster in the morning), which, being the procrastinating sort of person, I find pretty impressive.

The type locked up in the chase of the Kelsey, all ready to print. The type is Cloister Black in 24 and 36 point.

We had one bundle of handmade paper that was double-business-card size, so I printed two bookplates on each, and we will wet-tear them apart to simulate a deckle edge. The paper is not sized so wet-tearing works quite well. The unfortunate thing is that the paper is made from leftover pulp from a children’s’ papermaking workshop and so contains quite a bit of glitter. That is not of itself a problem, but some of the glitter was still stuck together in stacks as it would come out of the cutting die, thus making quite a thick hard lump in the paper. I had to pick these out not only because these lumps could damage the book the plate was put in, but could also damage the type I was using the print them.

The finished bookplates, still with wet spots from wet-tearing the two halves apart.

All the glitter on the floor that I had picked out of the paper.

I have a couple of short videos of the printing in progress, but I have do some editing and sound clean-up before putting them on YouTube.

Woo Hoo! Monotype U!

Posted on 2013/08/13 by kpmartin Posted in Kevin, Monotype Composition Caster, Monotype University 8 — 1 Comment ↓

The last week of August I will be heading to the mountains of West Virginia to attend Monotype University 8. This is a week-long intensive course on the operation of the Monotype Composition caster with emphasis on composition casting. This is actually an encore edition of the course which had been held somewhat regularly a few years ago. It is being run again because the instructor, Rich Hopkins, is concerned that most Monotype owners are using them for casting fonts and sorts, rather than composed text, the machine’s primary utility, and that the knowledge of doing composition casting will be lost if too few younger people take it up.

One thing Rich would like the students to bring along is any Monotype documentation they might have, so last Sunday I quickly made up a set of bookplates which I could put in all my books and brochures so they are less likely to be lost. I’m also making a catalogue of all my holdings so I know what duplicate items I have that I might be able to trade.

The pile of books I have to catalogue and put bookplates in. It turns out there are a total of 97 documents there.

I will also be bringing along my Monotype tool kit, a box of mystery parts, and some spare tools that other students might want for maintaining their casters.

Although the composition caster was originally designed to be driven by a 31-channel paper tape (or “ribbon”) punched by a separate keyboard, most of the casting work we will be doing will have the caster driven by a computer-controlled device which provides the compressed air bursts that would normally come through the holes punched in the ribbon. The computer control is more versatile than the mechanical keyboard in terms of making the caster do special work. It also gets around the near-impossibility of finding spools of blank ribbon to be punched.

The Monotype pump, all assembled and working!

Posted on 2013/08/06 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — No Comments ↓

This is the culmination of a long three-pronged refitting of the pump on my Monotype composition caster. The three parts were disassembling, cleaning, and reassembling the pump head mechanism, refitting a pump latch mechanism scavenged from another caster, and making an extended-stroke pump piston rod to increase the volume capacity of the pump.

I reassembled the whole mechanism and adjusted it per manufacturer’s instructions. I found that the pump lever connecting link (a32H) not only has the obvious top/bottom asymmetry (the top contains a spring and plunger to pre-load the pivot) but it also asymmetric side-to-side. The way I had things assembled, the levers could not move low enough to engage the pump body and piston rod. After turning it around everything fit nicely.

I already had the pot fired up (so I could remove the pump body and replace the piston) so I proceeded to cast some type. After fiddling with some adjustments (since I did not have the appropriate reference cards at hand) I had it casting some nice, near-solid type.

36-point Rockwell Antique capital N (31 points wide), cast using Linotype alloy. At the lower right is a type cut in half to see how solid it is.

A close-up of the type cut in half. The piece on the right is the raw sawn surface. On the left, filing the surface smooth reveals a few small bubbles near the face of the type, but not enough to weaken the face.

I was also weighing the individual types and had some that weighed more than the sectioned one, but to get that I had increased the pump pressure and was finding that many of the types had flash bordering on being an outright squirt from the pressure of the molten metal lifting the mat a bit. I am using an American bridge which has no provision for increasing the downward pressure on the mat.

Monotype piston rod finished

Posted on 2013/08/05 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — No Comments ↓

The extended-stroke piston rod I was making for my Monotype caster is now finished.

Now that it is off the mill, cleaned up, and has its handle put on it looks so much like it could have been a factory-made part. Except for the fact that the handle ended up a bit crooked.

But the proof of the part is in the pumping, so sometime this week I will be firing up the pot on my caster, finishing the re-installation of the pump mechanism, and after making all the appropriate adjustments that were disturbed by the disassembly, I will try casting 36-point capital Ms to see how solid they turn out.

Monotype piston rod—Mounted on mill, ready for cutting

Posted on 2013/08/02 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — No Comments ↓

After finishing one side of the extended-stroke piston rod for my Monotype, I took apart all the work holders and gave the mill a bit of a cleaning.

The rod has now been clamped down to the milling table with the first side down and the rod axis parallel to the mill X axis.

The only contact between the piston rod and milling table are the two flat spots at either end of the large-diameter area. The two square aluminum bars hold it down and prevent it from moving left-to-right, but the small contact area between the rod and the table made it difficult to stop the rod from turning about a vertical axis. To prevent this I added two hold-downs acting only as cleats at the far left end, and on the right end, used a machinist’s clamp tightened onto the piston rod and itself clamped to the milling table using a spacer and hold-downs.

When the picture was taken I had already done a few test passes cutting the flat on the top of the rod, to make sure I had all my coordinate origins correct and also that I had properly reversed the X and Y axes of the traversal path so it now does long Y traverses with successive small X stepovers.

Monotype piston rod milling half-completed

Posted on 2013/08/01 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — No Comments ↓

With the flats completed on the piston rod, it was time to mill the groove by which the piston is raised and lowered. This took quite a bit of time as I had the mill running at very conservative feed and speeds to ensure the sides of the groove would be accurate and the cutter would not go dull partway through the job.

I chose to leave the chips where they fell and added some oil to lubricate the cutting. The chips acted as a sponge to retain the oil, and the oil acted as a glue to retain the chips so all in all it worked well. The workpiece never got too hot to touch and the endmill did not get hot enough to make the oil smoke.

Once the groove had reached its requisite depth, I removed the rod from its vee block, and used a file and deburring tool to finish things off.

Now I have to mount the part onto the mill table with the flat side down. Rather than using a vee block again the part will be clamped directly to the table, ensuring that the flat surfaces on the other side are parallel to the ones already completed. To mount it this way I have to turn it so its axis is parallel to the mill X axis (on the vee block it was parallel to the Y axis) and as a result I have to modify all the CNC programming to swap the coordinates.

A new needle size

Posted on 2013/08/01 by kpmartin Posted in Things we sell — No Comments ↓

We noticed that we had a gap in our needle sizes: There was a big jump in diameter between the #17 needle (1.4mm) and the huge #15 needle (1.8mm). It may not seem like 0.4mm sounds like much but when you handle the needles the difference is very obvious.

We have filled the gap by adding a #16 (1.6mm) needle to our selection; it is a little over 2″ long, just slightly longer than the #17s. We are selling them for $0.45 each, or $1.05 for a pack of three.

Our needle selection, finest (at top) to thickest (at bottom). The apparent curvature of some of the needles is actually camera distortion.

Our “new” guillotine

Posted on 2013/07/28 by kpmartin Posted in Paper cutters — 2 Comments ↓

New to us, anyway, as it is older that the one it is replacing. This one is a Challenge Diamond 32″ guillotine with mechanical cut and manual clamp.

This machine has an after-market dual-hand control added so you have to have both hands away from the cutting area to initiate the cut, but once started the cut completes even if the handles are released, so if you move fast you can still cut off your fingers. It does not show from this angle, but the motor is mounted above the left of the back table (a bit visible below the clamp wheel) and a 3″ flat belt drives a flywheel and clutch at the lower left (again, part of the belt can be seen). Some day I should make a guard to cover that belt.

A small stress crack runs from the inside corner where the leg meets the arch and ends within the threaded bolt hold.

The machine needed some TLC when we got it. A lot of it was just cleaning things up, but there were also adjustments to to motor mount so the belt would run true, adjustments to the dual safety controls, and some repairs to the arch. On these older models, the arch (the curved part across the top) and its legs were cast as a single unit and with age tended to develop shrinkage cracks in the upper corners. This one had small cracks in three of the legs, and the fourth leg was broken through. This was repaired with epoxy, which appears to be strong enough to withstand the cutting forces involved. If it ever breaks I will drill vertical holes over each leg and insert a bolt, which is in fact how the newer cutters are constructed.

The area where the safety control had been attached turned out to be a void in the casting still filled with casting sand. Evidently the base of this machine was cast upside down and some of the casting sand came loose and lodged at the bottom of the mould cavity, which ultimately becomes the leg at the top of the base where the table mounts. I cleaned out all the sand I could and filled the hole with epoxy metal filler before drilling and tapping a new mounting hole.

The reasons we switched to this guillotine are mainly that we use (or perhaps it could be said abuse) it to cut up pulp sheets for shipping, and we found that most of our pulp sheets were just a bit too wide for the old 26″ cutter. Furthermore this motor runs natively on 240V single phase power, while the 26″ one has a three-phase motor and uses a VFD to run the motor on a single-phase power supply.

Finally working on the Monotype piston rod again

Posted on 2013/07/23 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — No Comments ↓

It has been a while but I finally got around to working on the extended-stroke piston rod for my Monotype caster’s pump tonight.

A while ago I had drilled and tapped the end hole for the handle. I was fortunate insofar as most of the rod fit through the hole in my drill press table, making the part easy to clamp for end drilling.

Since then I had milled one flat side on the very top of the rod using manual milling with the CNC unit just providing auto feed. This flat spot and its match on the other side provide a place for a wrench on the rod when necessary for removing the handle or the piston.

Because this is a small mill, it can’t cut much metal in a single pass, so I wrote a CNC program to cut the flats on the large-diameter section which allow the rod to be installed past the upper pump motion stop. This requires cutting off about 0.32″ of metal; at 0.010″ per pass making 32 passes I was certainly not going to do this manually.

This shows the mill partway through the process. When I quit this evening I still had 4 full-depth passes to go, followed by some shallower passes to the correct depth to give a good finished surface.

Once that is done I will modify the CNC program to cut the groove that the lugs on the piston lever run in. This is an even deeper cut but is only 7/8″ wide so overall it should go faster.

Then I will take the rod off the vee block, flip it over, and clamp it directly to the milling table to repeat all three flat cuts on the opposite side so the matching flats end up parallel to each other.

While the CNC program runs I am making a handle for this rod starting with a wooden file handle, into which I will fit a stub of 5/16NC threaded rod to match the threaded hole in the top end of the rod itself.