click the 'play' button when it appears to start the video
-- Mike
I've successfully moved my ShopBot CNC machine from the 3rd to the 1st floor... After cutting a large vacuum plenum to hold 4x8 foot by quarter-inch plywood sheets flat and solidly in place on the machine, I experimented yesterday by carving the dozen blocks for my (unimpressive image, I'm sorry to say) prints for Baren Forum Mythical Beasts Exchange (#27).
My kids gave me a nifty and TINY little all-digital video camera for XMAS, and I used it to shoot a 2 1/2 minute video of the computer-guided tool in action -- suitable for Windows Media Player, you can VIEW IT HERE, but you may want to turn down your volume as the router is very loud and obnoxious... What you'll see are some brief cuts of V-bit carving to outline the printing shapes, then clearing outside the V-carved areas with a 1/4" down-spiral -- I've also shown a couple of views of the control screen -- the first shows each line of program code as it's executed -- I think we're at about line 14,000 in the shot -- later there's a view showing the cutting head position in X (length) Y (width) and Z (height) coordinates.
In spite of the unimaginative image, the blocks turned out quite nicely! I'll be printing in pinks and greens for this one...
-- Mike Lyon
¶ 1:13 PM 1 comments links to this post
Finally, I had a major "AHA" night before last when Linda, my wife, hit the button to open our automatic garage door! YES, that's IT! So... Yesterday I did a little research on the Internet and found a nifty 'screw driven' garage door opener manufactured by Genie and widely available for about $170! I ran over to Home Depot and bought one -- they had about 50 of 'em on the shelf -- includes all the electronics and controls I needed, plus the linear actuator -- they sell so many of them that they are CHEAP for what's in the box, I think!
Last night and this morning I assembled the thing with some modifications to the limit switches so they'd work upside down which was the best way for me to mount the thing to my humidor drawer. Went together EASY and works like a charm! The seven inch per second action is pretty ideal for the way I want to use it, and I can actuate it by foot or by knee very easily -- even came with three remote control devices (which I don't imagine I'll need), so I can very easily open the drawer, register the paper to the block while the drawer holds the paper up above the inky block, hold it in place with both hands and hit the switch to close the drawer -- looks to me like it will work like a charm! I'm VERY happy today!
Here's the humidor in action (remote in one hand, camera in the other, animated from still photos as the drawer moved from closed to open) -- YOU GOTTA LOVE IT! That's a full 4x8 foot drawer moving easily back and forth -- it's working so very well!
Here's the view from underneath and behind the humidor with the drawer closed. The slide has actuated the garage drawer opener's 'open' limit switch at upper left and the linkage from the slide to the drawer is visible at the top left to center. The opener is supported at the far end by an aluminum triangle visible on the right, and the wire coil to the 'foot switch' is visible in the background.
Barely worth mentioning, as I might actually disconnect this and go with one of the remotes -- but this is the 'foot switch' -- modified by hot-melt gluing a small block of wood to the button so it extends far enough above the body of the thing to be 'clicked' by a tap of the foot...
-- Mike
¶ 6:23 PM 1 comments links to this post
March, 2004 printing table with sliding drawer humidor -- very sturdy table made of 1/4" plywood pieces which 'lock' together with simple hooked tabs and slots. Takes about five minutes to assemble or break down and packs into a 2" thick box for transporting.
This 'small' humidor is a sealed plexi box which dovetails onto the table. It has two open-top drawers with blotter in the bottom to keep paper damp and ready for printing. The bottom drawer slides open just over the block by pressing a foot 'pedal'. A sheet may then be pulled up over the lip of the drawer and registered onto the block while supported by the drawer. As the foot pedal is released, the drawer slides closed under the paper allowing it to settle onto the block very sweetly!
The new humidor is a very scaled up and mobile version of a traditional Japanese damp-stack. The bottom of the drawer is a 4 x 8 foot sheet of 6mm Coroplast (corrugated plastic sheet) which supports the damp stack -- 1st the damp blotter, then the dampended sheets (up to 4 x8 feet), then 'sealed' with another sheet of Coroplast. The top sheet will be supported by a simple lifting bar, similar to the way silkscreens are generally supported above the paper until the screen is dropped -- a pair of short retractable legs will hold the Coroplast above the paper stack during registration (while the drawer is open over the block). When the drawer is allowed to close, the 'legs' will be retracted by the structure of the drawer support and the Coroplast will settle back down, sealing the dampstack until it is time to print the next sheet. Printed sheets will be peeled up from the back and slid down over the front rail of the press into a similar drawer (not yet completed) which opens to the front mounted under the lower rails of the press. When a press pass is completed, the whole stack of printed papers will be picked up as a sandwich and flipped neatly back into the open paper delivery drawer (I HOPE)!
Because I want to be able to move freely around the press while brushing up the block, I've left a 24" aisle open between the press and the closed paper delivery drawer, so the drawer has to move quite a long way to arrive over the block! Each 'glide' of the large drawer is a bit over 87 inches long, stiffened by a 30x60mm aluminum extrusion. To prevent tipping, the drawer frame will be bolted into the floor (which is my hardware store visit, as they supplied me with the wrong size mounting hardware late last week -- ugh)...
side view of paper delivery drawer (slid back a bit to allow drilling into floor underway)
detail showing drawer corner and glide assembled to end plate -- simple 'stops' (not shown) are bolted into the ends of the fancy extrusions to prevent over-travel in either direction.
The drawers are quite simple -- the long front and back are 1" square x 1/8" aluminum tube with 1-1/2" x 1/8" flat bar screwed underneath to provide a lip for the CoroPlast bottom. The sides are 1-1/2" x 1/8" aluminum angle, and there's another bar mounted in the center between the front and back tubes to prevent bowing during open and close actions.
The drawer support is a simple trestle, held parallel by four lengths of 1/2" galvanized pipe tensioned with all-thread running the length and piercing the the 3/16" aluminum end plates and the 2" square tube legs -- tightened with four nuts and washers on each end. Bottom tube is bolted to legs and floor to prevent tipping.
press and paper delivery drawer which is shown partially open over the press bed
Next step: assemble the vacuum plenum for the press, assemble the bottom printed paper receiving drawer, and finally decide how to get the drawer to open and close while I hold the paper registered to the block with both hands! Getting REAL close to printing again, at last!
By the way, the press 'action' is a dream come true -- glides so easily and surely across the bed regardless of pressure setting -- I hope the thing PRINTS every bit as smoothly and beautifully as it seems to operate!
-- Mike
¶ 8:41 AM 4 comments links to this post
-- Mike
¶ 12:25 PM 4 comments links to this post
close-up of press drive
back-side assembly
drive side bottom view
top roller bearing guides test fitted OK
my very messy installation this morning
But one serious problem has now become apparent -- I originally conceived the press with the 1/8 inch bed held (like a drawer-bottom) by the inside slots of the main rails all around. Somehow I managed to under-dimension the press bed by about 3/8 inch, so it is able to slide around quite sloppily, and there's sufficient deflection side-to-side in the main rails to allow the bed to slip out of its track in the center. I've got 1/2 inch between the ends of the rollers and the side rails, though (to make it easier to keep the press bed swept free of wood chips and other debris), so I'll repair the problem when I attach some lengths of 1/4" x 2-1/4" plate to the inside of each top rail and then screw the bed down tight to those, using some flat-head machine screws countersunk into the bed very close to the rails. That should serve to stabilize both bed and side rails without too much work and without interfering with the smooth passage of the rollers across the bed.
-- Mike
-- Mike
¶ 6:57 AM 1 comments links to this post
Mike Lyon takes a quick breath after assembling the press onto its legs.
See previous description of this project
¶ 4:36 PM 2 comments links to this post
Late in 2004, I decided to produce large woodblock prints -- larger than I was able working alone and using a baren... Of course, I'd considered using assistants, but prefer to work alone and on my own schedule. So I began to think seriously about what sort of 'press' I might like to use. I tested the method on some medium scale (32") blocks for "Anthony" using my 30 x 60 inch bed etching press and the very lightest pressure and it worked much better than I'd expected, so I began by researching existing large intaglio presses (I'd first looked into the possibilty of building a huge hydraulic plate-press, but it appeared too heavy and much too costly). Large intaglio presses are also quite expensive, and the best were specifically designed for very thin plates and didn't have sufficient room between the bed and the top roller to accommodate both my blocks and the vacuum plenum I require to hold them flat. None of the manufacturers seemed willing to modify their designs to my specifications -- that came as something of a surprise to me, but I understand their reluctance better now. There were also some significant paper handling problems to overcome while registering large papers single-handed (to be described in a future posting).
Because of space considerations in my studio, a moving bed press was undesirable (requiring a footprint twice the length of the bed, so I first tried to design a very stiff bedded press with a single roller. Deflection of the bed seemed to me to be an insurmountable problem with this method, so I decided a more conventional two-roller scheme would be easier to engineer. I ultimately decided to design a somewhat unique two-roller 'wringer' type press in which the bed would be stationary and the rollers could move back and forth across the bed. Because the rollers work in opposition, the bed could be very thin -- just stiff enough to support the block prior to printing. I got some 'help' from Doug Forsythe's $25 plans to 'build your own etching press' -- these made for a more confident start!
One of the most important decisions was exactly 'how' the rollers could be made to accurately move back and forth along the press bed. There are many options for 'linear motion' solutions -- after much consideration and comparison, I selected some off-the-shelf components from Bishop Wisecarver (BWC.com) who not only provided the excellent (and expensive) aluminum extrusions I chose for the frame components, but also the compatible carriage and rail system which will convey the rollers along the frame rails.
carriage and rail illustration from Bishop Wisecarver
After many false starts and much consideration about exactly how large I might want to print, I decided to dimension the press to enable printing full size blocks cut from widely available 4x8 foot 'standard' sheets of plywood.
drawing of the final press plan
Getting the measurements right, figuring out how long things should be, how to make everything fit together, especially in the drive section where a number of parts had to be coordinated was challenging! For example, consider the two sprockets and chain in the drive -- that has always seemed so simple... Until I tried it! There are a HUGE number of choices of chain sizes and sprocket sizes, and after figuring out what weight of chain would work, then there's the desired mechanical advantage, and finally, you can't just measure chain to the nearest 16th inch, the links are fixed, so you have to calculate how many links, then the shaft centers can be figured and fit exactly... LOTS of new stuff to learn and calculate -- I must have tried 100 different combinations of chains and sprockets before deciding on one set which would work... In the process, I gave up on the configuration which would probably have been best -- placing a light weight chain inside each of the long rails which support everything, then meshing a sprocket into that chain on each side to drive the rollers along... That would'a been very cool, but I wasn't patient enough to redesign EVERYTHING in order to make it all fit... Compromises, compromises...
detail of the plan showing the rollers, bearings, sprockets, etc... kinda hard to read, eh?
So eventually I decided on a design I thought would work using as many 'off the shelf' components as I could find, and making the rest. Because I thought I could machine aluminum myself using the same CNC machine (from ShopBot Tools) I've been using to carve large blocks since March, 2004, I designed many of the parts to be cut out of 1/2" aluminum -- here's the drawing from which the parts were machined:
aluminum parts machining plan
Below is a photo of the machining in progress -- it was more difficult than I'd imagined, and I broke a few bits out of ignorance, but if I have to do it again, I'll be able to accomplish it much more easily. Live and learn!
machining the aluminum parts
view of machine and completed aluminum parts
the completed aluminum parts along with some of the bearings, handles, etc to be mounted
OK, I got a little fancy and engraved a logo on the faceplate, then filled it with pigment laden epoxy and sanded it down flush -- kinda pretty!
The rollers were another challenge... The bottom roller had to be machined to very close tolerance in order to exactly engage the press bed. I was also concerned about potential deflection in the 1.25" center shaft and performed some fairly complex calculations in order to satisfy myself that deflection would be minimal under load. Eventually I settled on a design which I had bid at several local machine shops. My design called for four large 'washers' to be welded to the shaft and the inside of schedule 80 black pipe, then for the pipe to be turned to precise dimension. But it turns out that schedule-80 pipe is unsuitable for turning, as it contains stresses which won't allow an accurate turning to be produced, so I had to go with much more expensive seamless DOM (drawn over mandril) tubing.
the drawing for fabrication of the rollers
the BEAUTIFUL nickel-plated rollers themselves!
view of assembly area, the 10 foot long press bed is at the top in the background, the aluminum extrusion rails are at the left, the two nickel plated steel rollers are visible as well
Detail of the roller ends -- a local machine shop did a fantastic job fabricating these, even turning down the welds to make smooth chamfers! They are almost stand-alone works of art themselves!
So I am finally actually assembling the thing! So far everything fits perfectly, and I'm feeling optimistic that it's all going to really work! The rails and carriages have been assembled to the frame sides, seem to work as I'd imagined, and look good!
Assembly detail showing BWC carriage mounted to carriage rail and carriage rail mounted to press rail, and press rail attached to leg and brace.
Total cost has been about $6,500 (yikes! But still SO MUCH cheaper than even a well-used intaglio press of similar size)
To be continued (Mike Lyon -- 10/31/2005)...
¶ 10:47 AM 4 comments links to this post
