Working On A New "Timber Frame" Design and Build.

I'm still in the design stages and ordering raw materials for the basic machine. This is my second build with the first being a modified version of the one Chris Fitch built for his Woodsmith article a few years back. The machine has done really well for what it is, and will be making some parts for this new design. It will be a hybrid of Baltic Birch plywood laminate structure and aluminum hard attach points and bolt plates. I am planning on pour in place rigid urethane foam for the base legs, gantry beam and columns, and possibly the table torsion box too.

The gantry carriage and Z axis will be fabricated from aluminum. Using 25mm rails on all axis, and X and Y being driven with Avid's Rack and Pinion drive system. Ball screw drive on the Z axis. A lot of details to still get through on the design but it is coming along. Cutting area is about 77" x 68" with the rotary axis being in the 77" length. The rotary axis is dropped and will have a 12" swing x 48"ish length.

Here are some screen shots from the CAD model.

I have been making some progress by cutting the aluminum components. Started out with everything I could fixture in the vise and then last night I set up on the first gantry side plate. Drilled holes and rough milled the bearing block pockets.

Hi Loren - Great to see a timber machine cutting AL. The flanges on the Z axis need to be solid. You loose quite a bit if stiffness when you truss it like you have done. Peter

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Originally Posted by peteeng

Hi Loren - Great to see a timber machine cutting AL. The flanges on the Z axis need to be solid. You loose quite a bit if stiffness when you truss it like you have done. Peter

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Thanks, I call it the Tortoise...slow but steady.

I know on the flanges on the Z axis. Made a compromise to add some stiffness but keep the weight lower on the moving Z axis. If it is a weak point in performance it will be easy to swap out or bond some sheet stock to the outsides.

Finished up cutting the pockets for the bearing blocks and started the profile. We had thunderstorms moving through last night so didn't get real far on it and shut it down so as not to lose power in the middle of cutting.

One gantry plate cut, one more to go. Had to babysit the profile cutting the whole time to keep chips vacuumed out of the slot.

Cut the other gantry side plate and then ran this plate. Just some holes and counter bores. It is the Y axis carriage base plate. Trying out some jeweled engine turn technique to add a little bling to the machined aluminum components.

https://www.youtube.com/watch?v=2xbE8NaDfrM

Starting to fit parts together for the Z axis. A lot of hole drilling and tapping. Not a lot of fun with little taps.

The Y axis carriage and Z axis are coming along. Next is more detail work (finish drilling holes to size and tapping holes) on the rest of the parts for the Z axis carriage.

The Y Carriage & Z Axis is nearly complete. I still need to make the air cylinder rod mount and the vertical bumper. Then time to clean up my mess and get ready to start building the machine base.

I started the construction of the base, starting with the legs. They will be filled with rigid urethane foam.

Hi Loren - Be careful with PU foam., It continues to grow for a long time after its poured. I had a boat once and its bunks where quite humped due to overfilling and long curing time. I also used PU foaming glue once on an archway and it consisted of 10 laminates of 10mm ply. It grew over 3mm thicker in a period of 6 months... Why fill with foam, it will not contribute to the legs stiffness? Peter

I have worked in industries over the years that used rigid PU for making structural insulated panels. PU can really build some forces over larger areas, especially if overfilled. Like break stuff apart forces!

It will dampen the panels and add some stiffness to the face sheets, which I wanted.

I'm not a fan of the foaming PU adhesives just because of the problems you had with your laminate.

Hi Loren - I'm about to cut some al plate. What was your feeds speeds and tooling you used for your side plates/columns? Did you cut dry? I'm making a small machine mainly from ply/al laminate. Then may make the next one from al plate.

The PU adhesive is a great adhesive, sticks to everything! But its clean up and squeeze out is a pain to deal with. Will use epoxy on this build, friendlier & no growth...Peter

I agree the PU adhesives are great at bonding, but the foaming kind are like you said a pain to clean up.

For an adaptive type tool path I use .015" radial cut and .030 axial 72 IPM and rpm 8000-10000 using a 1/4" three flite carbide end mill and cutting dry.

For cutting the profile, I was basically slot cutting so I used a .015" axial DOC and made 4 passes at depth, stepping over .015" with each additional pass to open up the slot and create some cutter relief as I went deeper. I used 1/4" O-flute carbide cutter 18K rpm and 30 ipm. On the profile cut, I baby sat it the whole time with a shop vac keeping chips cleared out of the slot, so I wasn't re-cutting them and used isopropyl alcohol from a spray bottle as a coolant. I tried the profile cutting dry and I had some close calls with chip welding.

Those chip loads and feeds don't stress the machine, and does a fair job on finish for a home built wood frames machine. I did a whole bunch of drilling on the machine to which saved me a ton of hand layout work. I used 1/8" and 1/4" stub carbide drills running the router as slow as it would go at 8k rpm. using peck drilling cycles and light chip loads and alcohol for coolant, which I like because it evaporates and doesn't make as much of a mess as oil based products.

Like I said "the Tortoise"...slow but steady

Thanks Loren - slowly slowly is a good plan. I hadn't thought about stepping over the cuts in the profiling good idea. By 0-flute do you mean 1 flute? When I peck Al I cook the drill usually (too much speed can't slow the spindle slow enough) so more metho needed.... Peter

Yes, a single flute cutter. This is the cutter 51481-Z Solid Carbide CNC Spiral 'O' Flute, Aluminum Cutting 1/4 Dia x 1-1/4 x 1/4 Shank Up-Cut ZrN Coated Router Bit

My peek drilling cycle, 8k rpm (as slow as the Dewalt will run) .030" pecking depth, full retract every .060", and I will have to go back and look at my programs to see what I had for feed rate. It was pretty slow. The chips are small, but I am cutting and not just rubbing and dulling the drill. Again I was using isopropyl alcohol for coolant and carbide drills. The drills are solid carbide, which is part of how I got away with it. I did all the final hole size drilling on the drill press using the router drilled holes as pilots and it worked out really well.

Hi Loren - I have used a centre drill for piloting before that worked well. Then drill on press. All my drills are HSS so I'll try some carbide on this project. I've only just started to explore aluminium cutting on my latest machine. My next machine project is to make Al/plywood/al laminate parts and solid al parts these will need cutting. I think the ZrN coating is a clue as well, limits pick up....Ta Peter

https://www.aliexpress.com/item/32954411364.html I was looking at something like this for drilling....

I was feeding the 1/8" drill at 2.5 IPM and the 1/4" drill at 3 IPM. 8000 rpm. The ZrN coating coating helps, but chips evacuation is critical.

That would be a nice spindle for drilling.

Are you laminating the AL/PLY/AL panels or purchasing?

Hi Loren - I'll make the panels myself. I'll rough the sheets down and use epoxy and vacuum bag to make rough parts then finish profile on router. Peter