I want to make some templates for band-sawing lathe blanks. These are just large circles with a hole in the center for a nail, but I need some sizes that are too large for the GF to cut. (To cut these templates on the bandsaw requires a circle-cutting jig and if I had one of those I wouldn’t need the templates. I figure for what I paid for my GF I should be exempt from making/buying a circle cutting jig, right?)
The largest I’ll need is 16" diameter which will involve two 8-inch semi-circles which I’ll then join together. I’d like something sturdy so I was thinking of a box joint which would provide lots of glue surface. I was even thinking about using a locking pattern like a dovetail but I do not yet have the Inkscape chops to do that.
So my questions are…
Does draftboard edge-glue well?
If so is it necessary to sand off the laser marks prior to gluing?
Anyone know of a box generator that will do an interlocking joint?
My fallback here is to use the thinner draft board to make two circles, orient them with the joints of the upper and lower circle at right angles and glue them at the faces. But I thought I’d ask about glue performance and maybe get some practice making locking joints before caving in and take the easy way out.
I did not sand the edges. Oh…I also didn’t use joints. Just figured I’d show an example of a circle I made with draftboard. FYI, this thing has seen very heavy use over the last 2 years, and it’s still together.
Two matching halves, keyed to help you keep them aligned. Almost there. Now color code the inner nail circle to be different from the outer shape so that they are separate steps. You want the nail hole cut first for alignment purposes.
The idea would be to cut two pairs of semicircles, then glue them to each other, rotating the top layer by ~90 degrees so that the joints don’t overlap and make a weak overall circle. You might want to adjust the diameter of the nail hole – I made it 1/8", which may be too much. Just be sure that if you do resize it that you center it exactly where the old one was. I’d use guides to ensure you don’t miss.
I only needed to exceed one of the GF dimensions and you did two. Very cool!
When I did the cedar box a while back I edge-glued the planks and it worked perfectly so I thought I might get away with that here. Based on your and @evansd2 feedback I’m now planning to do this project as two layers. Glad to see face-gluing these worked so well.
What are you using it for? I don’t see a center hole so I’m guessing edge guide for a bearing-guided router bit?
Tons! Thanks! I really appreciate your whipping up a tutorial from scratch. I will definitely try this later tonight. I’m going to refrain from just downloading the file and instead run through the steps so I get some practice. At least if I hose it up I will end up with draftboard pieces large enough to reuse for something else. Will post results soon.
My husband wanted a perfect circle to put on the backs of his rims to see if there were dents anywhere so he can hammer them out. I use it as a tabletop to spray paint stuff when he isn’t looking…it’s probably been crushed by the car a few times too. But it’s still perfectly flat.
Good question! Two reasons. The first, and perhaps most trivial, is that given what I paid for the GF I figure I should be exempt from having to make/buy a circle cutting jig for the bandsaw. To some extent I feel entitled to NOT buy or make a jig. If you don’t agree with me on that, please call me Karen and fetch the manager!
The other, more practical, reason is that the stuff I want to cut lathe blanks from is usually green logs that have been roughed with a chainsaw. A circle cutting jig is best suited to S2S or better milled stock up to a few inches thick with a flat, smooth bottom, and when the desired end result is as close to a perfect circle as possible.
It doesn’t work as well when the timber in question has a rough bottom, is 8~14 inches tall, and doesn’t need to be perfectly round since we’ll take care of that on the lathe. Rather than cutting a continuous circle like a jig, I usually cut these by nailing a template to the top of the wood and then making many cuts that approach the template tangentially. Not to mention the jig reduces the maximum height of the wood I can cut and sometimes I really need every bit of that. With a template I can run with the wood just under the blade guides and the template against the side of the outer guide and get all my available height.
Also…that template jig in the picture? Not sure how long it’ll last cutting green wood. I cut some river birch last month that soaked the bandsaw and gave me a lathe-shower when I rough turned it. The template sits above the wood so doesn’t get as wet, but it is intended to be consumable and replaced as needed anyway.
The whole “wet wood” thing was the toughest part of woodturning to learn for me. Not to mention it adds a LOT of maintenance chores fighting rust on the power tools. Good thing the only power tools I really use with wet wood are the lathe and bandsaw. I would HATE to have to clean wet gunk out of the innards of the table saw!
That was my second guess. Router guide first, obviously. Then hammering out rims is the natural second choice.
Also its a great reason to use the GF - getting a circle that has at least as much precision as the rim. Add a hole in the center and it would be great for tuning bicycle rims, too!
My Hubs got me one for our 25th anniversary, so I’ve been devouring YouTube videos and learning to turn on it. I haven’t tackled any large bowls yet, but I did manage to make a small live-edge bowl the other day without launching it across the shop or breaking off too much bark, so I’m feeling super proud of myself right now!
Just curious, why won’t a nail and a 16” piece of string tied into a loop do the job? Couldn’t you just tap a nail into the wood, then put a pen in the loop and draw a circle?
For that matter couldn’t a 1” rectangle of wood with two holes 8” apart do the job? Tap a nail into the wood, put one of the holes in the rectangle over the nail, put your pen/pencil in the other and zip zip circle…?
Not hard to imagine a ruler with holes every inch allowing you to make circles of many sizes? You could draw 38” diameter circles if you made a 19” ruler…
Congrats on the lathe. What an awesome anniversary present! (Of course it tends to generate lots of presents back and you do good work so he may have had an ulterior motive.)
One of the things I made on the GF that is lathe-related were some chuck templates for several sizes of jaws. There’s two round semi-circle cut-outs used to size the min/max tenon and two pointers used for sizing mortises. These are sized into templates for 2 inch, 3 inch and 4 inch jaws (if I remember correctly). They are used on almost everything I turn that isn’t a pen.
I will look for the SVG files and post them in a Free Designs topic if I can locate them. Meantime, I wrote a post about choosing the right respirator you might like because, well, lungs are kinda important and pulmonologists are in short supply these days.
Also, if you want to do segmented turning have a look at the calculator over at BlockLayer.com. Once you calculate the segment size you need, the site provides an SVG of the segment. When I first found it I asked the site owner to also provide an SVG of the entire ring which he has done.
Both of these are useful GF projects. If you print the full ring from the SVG you get all of the segments plus the perimeter from which they were cut. The duplicate segment templates are not terribly useful but when you actually cut the wood segments you can use the template you cut in the GF to hold and align them as you assemble the ring.
But just printing one segment template is really useful. Use the width of it to set the rip width, then use the angled face to set the miter angle. Lastly, use the long side to set the distance between the blade and the stop block.
Obviously, the larger the segment the more accurate it is as a setup tool. Also, note the power cord is parked next to the blade for all setup operations involving the blade.
Originally I didn’t think the GF was going to be this much help on the lathe but in hindsight that turns out to have been lack of imagination on my part.
Using a string compass would map the circle onto the convex outer bark, leaving me an unusable oval cylinder. What I need is a round vertical cylinder, even though the top slopes down from a central ridge. Quick solution - nail a round template to the top of the log and use it as a cutting guide.
I’ve been using paper plates and plastic lids for the tiny logs like this. When the tree trunk is 20" ~ 30" to start, the work piece ends up being almost that wide and half as tall. Paper plates are too small for a log that size. The widest cylinder I can fit between spindles on the lathe is about 16" diameter so I need templates up to that size.
This also shows another reason why a circle jig won’t work. The bandsaw throat is 14" and the diagonal of my rough-cut log can be 40" or more. So I whittle away the corners by making cuts tangential to the template. It isn’t until it is about 3/4 cut that it is small enough to spin a circle on the bandsaw.
Some turners do the initial shaping with the chainsaw and have a rough cylinder by the time they get to the bandsaw. I prefer shaping the log on the bandsaw because it often leaves me off-cuts large enough to make small bowls or cups. The circle template I make on the GF will be a tremendous help with this.
Can’t, really. At best I minimize it by not including the pith and making the walls thin so the shape changes don’t over-stress the wood. The bowl in the previous photo is now quite a bit oval and had developed cracks, but the live-edge with the bark renders these as part of the “rustic” design.
The walls of this bowl are a bit thinner than the platter rim (maybe 1/4 ~ 3/8 inch) and it has very little movement or cracking after several weeks. (This log was roughed out with a paper plate and was my inspiration for wanting to laser-cut circle templates, by the way.)
Sometimes the cracks are intentionally part of the design. Like when the wood is too damaged to turn safely. This log had serious cracks so I kiln dried it (which made them even worse) then stabilized it by casting it in colored resin.
That said, I was given a coring system for Christmas so I am going to try rough-turning and sealing some bowls. Then after they dry for a year or so they are stable after turning and hold shape without cracking. I’ll try to remember to come back in 2 years and post pix.
Hey @evansd2 I was going to post back here with my results from using your tutorial then my plan went all to hell, but in a good way. I found a 18x48 scrap of 1/4 Baltic Birch and remembered I have pass-through slots.
I’m thrilled to report that the pass-through positioning worked PERFECTLY and the endpoints of my two circle segments joined seamlessly. On the other hand, d’oh! Why didn’t I think of that?
(On the other other hand, why can’t we get positioning this precise as a general feature? My laser engraver paints a preview outline so the workpiece can be positioned precisely, and because of that it siphons off a LOT of the work I thought I’d be using the GF for.)
Anyway, I just wanted to say I did practice with the tutorial you provided and was able to complete the task. True, it looked like something a 5-yo would draw and hang on the fridge, but all the nodes were connected into a single path that would have cut properly if I hadn’t realized I have pass-through slots. Here’s a big THANK YOU for that!
