4th Axis Work Holder Experience by Larry Thomson
August 23, 2018
By way of introduction, I started woodworking when I retired 6 years ago. One of my first projects was a chest of drawers from plans I downloaded — because I didn’t know any better, I didn’t realize what a ‘shaker design’ entailed — it was doing that project that I fell in love with what you can do with a router. Fast forward 4 years and I’m trying to decide whether I need a lathe so I can make better table legs and I get this email about a ‘Router Boss’ and the 4th axis attachment and the more I look at it — the more intrigued I become — now I was perfectly satisfied with my Kreg router table, lift, Milwaukee 5625 router — but this router boss looked like a better mousetrap — and I guess the fact that I am doing this write-up tells the rest of the story …. another point I need to make is that I have only been doing this stuff for 6 years, I am completely self-taught — save some videos from WWGOA — which means the only way I know how to do things is how it works for me — not the right way, not the fastest way, not the accepted way — just the way it has worked — for better or worse — for me — it is important that you keep that in mind as we go forward —
The project that set this all in motion was a desk for my new son-in-law — a lot of what I do is make furniture for my kids — and I envisioned the sides and front to be raised panels with round legs/columns at the corners — so the first thing I did was create a round leg —
But let’s start at the beginning — I think if you haven’t looked at the 4th axis holder video available on the chipsfly.com website — now would be a good time to view it — it covers well the basics of setup and cutting a table leg — not much hardware is needed
— the tailstock, the bar, the rotating headstock adapter, couple of bolts, couple of spacers —
For everything I have done I have used option 2 of the 4 mounting choices — where you attach everything directly to the sliding bar of the router boss — the only difficult part for me is managing the weight while I try and get started 2 bolts that are 2 feet apart without dropping the bolts and/or spacers in the process — hence, — a spade end fitting across the bolt will keep everything in place until you get the bolt started – the picture below shows all the pieces in place —
You might notice an add-on to the basic router boss — I bought a set of under-counter LED lights and adapted them to hang from the corners of the baseplate — I find it really helps — I’ve put a link to the product in the resource notes at the end —
So let’s look at the stock we will start with — for the legs of the desk — I wanted 2 1/2″ diameter finished legs 30″ long – it pushed the limits of the 4th axis on both specs — to get around the 2 1/8″ limit stated in the video — I simply did a round off [ 1/2″] on the 4 corners of the stock — a 2 1/8″ square yields a 3″ diagonal — so if you can keep the diagonal less than 3″ — you can expand the square size — and using a round off on the corners does just that — you’re going to cut the corners off anyway — I also had to trim the square of the end down to fit in the headstock adapter — getting the 30″ length just meant putting the tailstock and headstock at the absolute limit of the bar – The pictures below illustrate both points —
My current project is a standup armoire for my wife, Becky — I am working from a picture of something she saw on the web – a central case with 7 drawers, and 2 swing out side panels to hold necklaces, chains, etc — on the front of the side panels
— and mounted per the video
— I use an up-cut spiral bit, 1/2″ for the cuts with the default depth of cut set to 1/16″ — I also found a CMT collet extender to be very useful — it spins true and often gives better visibility from above of the ongoing cut — [link in resource notes]
— Set the depth of cut on one of the corners and try to remember to check the alignment of the workpiece at the ends just to confirm — I also put a digital cube level on the piece to confirm level — finally, set a stop on the head stock end and we’re ready to go— I continue with 1/16″ cuts until almost done — then I reduce to 1/32″ cuts until I have just achieved a full round — a finishing cut is done at .010″ — very slowly — you can see the tool marks — Below picture is after the sanding technique demonstrated in the video — it helps a lot — but there is still more sanding needed to eliminate the rings entirely — I think reversing the rotation — a climb cut — leaves more tool marks — for the 1/16″ cuts — I do one rotation of the transverse handle every 15 sec or so — I call that fast — leaves big tool marks — rings around the workpiece — when I shift to 1/32″ — I slow down considerably — 45 sec for 1 rotation — I think it is a pay me now, pay me later situation — faster cuts leaves bigger tool marks, takes longer to sand them all out — if I slow down now — I sand less later — I set the successive cuts using the brass gauge bars I bought with the router boss — easy, quick, reproducible — I always try to look at the progress of the cuts every so often — the ‘cut’ and ‘uncut’ stripes should be straight, uniform, symmetrical — however you want to phrase it — any asymmetry in the width of either from one end of the stock to the other tells me I have a misalignment somewhere —
When I did these, I worried that the rounded off corners [piece A] might compromise the secure fit in the headstock adapter — it looks like it wants square corners — so on 1 piece — I modified the end so the last 1/2″ had sharp corners [piece C] — on another — I stopped the round off short of the end of the piece — it was 2 9/16″ on 1 side so I had to also cut it down a little to fit in the adapter [piece D]— Can’t say I noticed any difference during the cut or in the appearance of the final piece after — don’t think it mattered — however, one aspect was consistent across the 4 round legs — the diameter of the tailstock end was 3/128″ smaller than the diameter of the headstock end — using an iGaging caliper tool [aside: fantastic calipers — big numbers — fractional and decimal inches] — my best guess is that the headstock end must have had some give in the plastic cup — the pressure of the cut pushed the stock down as the bit approached the headstock end causing the larger diameter — so maybe the rounding off of the corners needs to be re-visited — also, piece D was slightly rectangular in size — by 1/4″ — the plastic cup looks like it wants square ends — agreed — 3/128″ is not a deal breaker — sometimes all this digital input can make one crazy – another option would be to use a standard chuck from Sherline in the headstock.
Next step is to cut these exactly in half and mount them on the front of the side panel doors — my wife didn’t want any ‘dust collectors’ i.e. profiles cut into the pieces — I was able to talk her into a collar around the top , bottom and middle to hide the junction between the 2 pieces — so I have only played with cutting profiles – the below picture shows my total experience — The profile bits were bought from Magnate — there’s a point cutting, a v groove and a cove bit — I remember it was hard to figure out what I needed — what the profile from each bit would look like – note that the CMT collet extender is necessary to get the bits down to the stock — the overall lengths are less than 3″ — maybe next time ….
I think that about wraps it up — I hope you found my ramblings useful — my fervent hope is that stuff like this will spur conversations among Router Boss users — opportunities to share experiences, tips and techniques — I firmly believe that: 1) it is a fantastic tool and 2) I am only scratching the surface of how it can help me to be a better woodworker.
September 6, 2018
Not necessarily related to the blog post — more in the category of what you can do with a router boss that you can’t do with anything else — rephrase — what I do with a router boss because I can’t figure out any other way to do it —
I took the columns made in the blog post and cut them in half — I have to join 2 together so the half-column can then be mounted to the front face of the side panels of the armoire — don’t have a band saw so I had to do the half cut on my table saw — didn’t think i could manage a 38″ long pieces thru the table saw so I did the half cut on each of the 22″ pieces — the columns were turned to 2″ (+/- 1/128) so they would match — the half cuts were done to maintain the 1″ radius — side panels are 2.5″ wide
— now that I have them cut — how do I join the two pieces together so they match and won’t fall apart
I decided to cut a mortice in each of the half pieces — 1/4″ wide, 1/2″ long, 3/8″ deep — and make a floating tenon — this will register the two together and give the joint a little strength — so i clamped the two pieces side by side — registered to the top, and perfectly parallel to the plane of the bit — registered the bit to the flat side and moved it 1/2″ toward the inside using the spacers — moved L/R until I had what I thought was center and dropped the bit to just touch — moved + 1/8″ – to cut one side of the mortice — moved to – 1/8″ using the DRO – to cut the other side of the mortise — back to “0” — cleaned out the center and the sides — moved to the second piece and repeated the process — final result shown above — you can see the clamping — I simply don’t know how I could have done this activity with the precision I needed on any other device — not counting cutting, moving, checking, moving back, and final cutting – all without any loss of precision.— these pictures show the tenon in place and the joint put together — to my eye, there is no discernible difference across the joint — they fit perfectly — the key is the ability to secure a setup, the ability to confirm the setup as often as necessary, the ability to control the cuts, and the ability to see everything as you do it — all with a final precision of better than 1/64″
You say it in one of the videos — if you can imagine it — you can do it with a router boss — it is just so much fun proving that that is true —