Baltic Birch drum for etching press part 1
So, making a drum for your printing press out of plywood is a perfectly acceptable option for the printing press you want to make. Why would you want a wood drum vs a metal drum? The best thing about the baltic birch drum besides the weight, is the fact that you can make it in a wood shop yourself, instead of buying one or needing to have a custom drum made by a machine shop. The baltic birch plywood drum will last, and can pull etchings – all day long. Craft & Concept printing presses use this method for all the wooden printing presses we have made. After so much interest in how to make the drum, this is the first post about how to make the drums with your own wood or metal lathe. So here is a very quick step by step overview on how to make the drum without a cnc router cutting out the disks, and without a machine shop making the shaft, or turning down the drum. In this post, we will go over a method for making the drum without using a “machined shaft.” For this method a simple piece of solid steel is used as the axle for the printing press drum.
Step 1 : Choosing the metal stock
Since you are not using a machined shaft (see part 2 post to see the advantages and pictures of a drum with a machined shaft), you will need to make sure that the steel rod used for the axle is straight. Roll the metal on a surface you know is flat, and watch as it rolls to see if it wobbles or has any odd features while rolling. If you can see it with the naked eye, it is not true or straight enough to make prints. So after you have found two pieces of steel of appropriate length for both drums, you will need to make the plywood rings.
Step 2 : Making the baltic birch rings
After you have decided what size and length of drums you will make, you will have to plan out how much plywood is needed. After you have the baltic birch plywood, cut the ply down to squares that are a little bit bigger than the circles you will eventually need. Next, find the centers of the plywood squares and mark them with a center pouch or awl. Now make a circle with your compass off the center point. Next you will drill a hole in the center point, that is the same size of the metal rod you have chosen for your drum axle. Test the hole on the metal rod to see how well it fits, and how easily it slides. Now you are ready to use the circle made with the compass, to cut out circles on the band saw. Cut outside of the lines you have drawn for the circles, since they represent the final size you want the drum to be in the end. Now you have a stack of rough cut circles, with circles drilled out in the center.
Step 3 : The glue up
The next step is to plan out where you want the drum “placed” on the axle. After marking that, you need to prepare and plan for your glue up. Use wood glue (titebond 2 or 3) to glue the wood rings together on the axle. After you have all the disks glued up on the axle, in the right place, make sure you clean and dry the metal off as best you can on both ends. After 24 hours for the glue to cure (for titebond 2), its time for the lathe.
Step 4 : How to chuck the drum up in the lathe without the machined shaft – see part 2 for setup with machined shaft
You will see photos showing pillow block bearings holding the drum up, instead of the the drum being held by the sander. If you are not using a proper machined shaft to make your printing press for cost reasons, having a center point in the shaft will be next to impossible to go off of, which is usually what you do with all lathe work (work off the center point). However, in the pictures show here, the solid stock is chucked straight into the lathe itself, and a jig built around onto the lathe to hold it with the bearings, instead of the sander. After finding the center, and therefore working out any vibrations, having a strong enough jig to support everything, your finally ready to cut with this major DIY setup! As a lengthy side note, this can be done on a wood lathe as well – The same sort of jig employed, and a fence for a router with a straight cut bit to run the face of the drum while the lathe is turning. Yeah, it can be done very dangerously, or safely. I am hoping to have a youtube video up at some point. The main thing about doing any of this is the speed of the turning. If you are cutting the drum with a router bit while turning the drum on the lathe, the appropriate speed of both needs to be found.
Step 5 : Milling
Now to the final steps. In step 4 the wood lathe option with the router is true and round, because the router rides a fence along the lathe, ensuring the drum is the same dimension throughout. The beauty of a metal lathe if you have access to one, is that the cutter head does this instead of the router, and has fine tune adjustments for turning down the drum to the exact finish you want. Take it easy the first couple of passes, getting rid of all the bumps and ridges of glue or uneven cuts in your disks. If you used a cnc or a jig to make your plywood disks, your drum is already be close to true. Either way, the drum will end up the same in the end. If you don’t have access to whatever you might want/need to make the perfect circles for your drum glue up, then you will just be spending more time on the lathe cutting it down. Ok. Mind your bit. You will have to find the right combination of speed on the turn of your cut and the speed of the lathe. Take very little off each pass at first, until you start to revel the clean baltic birch drum underneath.
Step 6 : Finishing and Sanding
After you have cut through all the flats spots and glue marks, its time to mill your drum down to the dia. you designed for your printing press. The only one that will be crucial to hit a mark for, is the bottom drum if you are making an etching press. For the final cuts take off very little, almost producing a fuze with the blade as your trim the drum to near final size. You will use sandpaper to take it to the last bit. The best way is probably to spray adhere a pieces of sandpaper to 3/4″ mdf that are flat, and using them with your hand to sand the drum while it is running and the cutter head is to the side out of play. After the drum is done, you can drill holes on the edge of the drum face, into the axle and instal a set screw or pin of some kind to insure they are locked together. Be mindful of how fine you sand the drum down to as far as grit. You need to know if you want a drum sanded to 120, or if you want it sanded to 400. The amount of finish that the drum needs to have, is completely overstated. I usually sand them to 120 or 150 if the etching press does not have a gear and track for the bed, as most simple printing press don’t. If a geared system like this is part of the press, sanding the drum to a much finer finish may make the drum nicer from a craft point of view, but does not affect the print if the drum is turned true. And so if fact if you do not have a geared system, sanding less with the sandpaper should result in a printing drum that is consistent, and ready for making all kinds of prints. If this seemed way to much work to save some money on making the press, check out part 2 to see the benefits of using a purchased machined shaft.