Woodworking Router SBD0905

[scratchbuilt_designs]

As mentioned in my new member introduction post I am about to replace my Sorotec CL0805 router with a DIY build, custom fit to my needs.

Not that I really have to. The CL0805 is after the modifications I have already done in the meantime a decent router and I was able to mill all the aluminum and even the steel parts, which I needed for my UHPC router build on it.

It is just a personal issue, that I do not want to have a Sorotec product in my basement anymore. 🤔

I want to use my UHPC router strictly for metal and plastics. So the new router will be used for all sorts of CNC woodwork.

My first idea was to incorporate an automatically height adjustable dust shoe (Marius Hornberger style). But that design would have consumed too much Y-travel. Therefore, I currently plan to use a conventional system...
(btw. I am loading/unloading work pieces from the side, that's why the bed axis is X and the gantry axis Y in my world...)

There are some limitations that the design of the new router needs to respect and the most important one is the available space.
It has to fit into the same enclosure where currently the Sorotec sits in.

I would have preferred a little bit more travel in Y, but one other design aspect was to achieve a high degree in rigidity and stiffness. Also, peripherals like drag chains consume a certain amount of space as well...

Here are some key specs:

Milling area 900x500x150mm
Hiwin HGR20R rails on all axes
TBI DFU2005 ball screws on X and Y, DFU1605 on Z
400W JMC servo on X, 200W on Y, 180W with brake on Z
12m/min rapid movement
Total weight 180kg

[scratchbuilt_designs]

Sorry...post was doubled

[scratchbuilt_designs]

My design goal was to have a gantry with a very high stiffness. Therefore, I made the gantry beam out of a box structure, which has a high torsional rigidity.

The main part of it is the plate to which the linear rails are bolted to. This is illustrated as blue in the renderings. This is one 25mm thick piece and the 25mm thick side plates are bolted to it from two sides.
The huge cut-out is used for other parts in the build...

In addition this plate is reinforced with two 25x40mm aluminum strips into which the alignment edges for the rails are milled.

The backsides of the two side plates are connected with a 10mm thick plate, which forms the box. Two 25mm thick intermediate ribs, evenly spaced reinforce the whole box structure.
Two thin profiles, top and bottom, close the box and protect the servo from dust.

The servo is fixed to one side plate and the whole spacer unit with the bearings and the intermediate shaft can be adjusted with four grub screws from the front, in order to tighten the timing belt before fixing the servo.
I went for this rather unusual design, because I did not want to have a cut-out for the servo in the side plate, which would have been necessary, if the pulley was mounted directly to the servo...

[scratchbuilt_designs]

The Z-axis is basically a copy of the Z-axis on my UHPC router. A fairly rigid box structure, which goes onto the Y-axis cross plate. The linear rails are bolted to this fixed part.

The spindle mounting plate with the carriers is the moving part. It is a 15mm thick aluminium plate with two 15x45mm reinforcement strips, which act as well as spacers to have enough clearance for the BS nut.

For Z-axis design, I really prefer moving carriers over moving rails. I have 150mm gantry height and 170mm Z-travel.
Fully down, the bottom of the tool holder is 20mm above the fixture plate. No need to lower this completly, since almost every of my tools has a stick-out which is longer...
Fully up, the tool holder is 40mm above the Z-axis bottom, which is flush with the gantry bottom. Means an endmill with 40mm stick-out is flush with the gantry bottom.
With such a design I can make use of the complete 150mm gantry height. How useful this is, you can see in the last pic, which is my current router.

On a Z-axis with moving rails you'd loose with such an endmill roughly 65-70mm of the gantry height, depending on how high the spindle sits on the mounting plate. But usually the holder or the collet nut is below the bottom of the plate for better access of the wrenches...

I will also add an Opt laser to the machine, which can be easily removed when milling.
There is a magnetic docking station for a laser, which is a neat feature.

Dust shoe will also be removable and hold in place with magnets.
I design two permanent air cooling/cleaning nozzles to one side, so dust is blown away from the enclosure door.
A lesson learnt from my current router.

But there is as well a provision for a mist coolant hose...just in case

[scratchbuilt_designs]

The machine bed is basically a frame, made out of two 1155mm long 80x80mm heavy duty aluminum profiles, which are connected by three 280mm long 80x40mm heavy duty profiles and one 80x40mm aluminum block. This massive block carries the MBA-15D servo motor bracket with the FK15 fixed bearing block and the 400W JMC servo.

At each end of this frame is a 15x100x585mm end plate, one with the FF15 loose bearing block.

Ball screw is a TBI DFU2005 with a double nut. I have the same on my UHPC router and I could not measure any backlash (at least with my equipment...)

The Hiwin HGR20R rails with pre-loaded HGW20CCZAH flange carriers are bolted to 20x80mm aluminum strips, which in turn are bolted to the 80x80mm profiles. The carriers have KK heavy duty seals in order to deal with the fine wood dust.

Neither the rails, nor the aluminum profiles are perfectly straight, so in order to have a halfway precise machine you need to mill a flat seat and an alignment edge for the rails.

But rather than further weakening the already thin profiles, I prefer to add these strips. They are first bolted to the profiles and then the flat surface with a straight edge is milled.

Before that the profiles are filled with epoxy and a 40x40mm steel bar. This way I can add 25kg to the bed. With the 25mm thick acetal fixture plate the whole bed is 100kg

The machine feet with a rubber damper will be bolted to the work bench from the bottom, so wobbling should be no issue...

[scratchbuilt_designs]

I have already filled the profiles and this worked reasonably well.

Calculated the quantity (about 1250ml), mixed and poured the expoxy in three batches and then just added the steel bar.
The expoxy than rose just an inch below the top and I poured the rest.
Better this way than to have a nasty spill...

The profile is obviously closed on one side. I used a piece of phenol coated plywood with a layer of packing tape (just in case the release agent fails), which is bolted to the profile.
The steel bar has two holes, top and bottom. One slides into a wooden dowel pin at the bottom (for centering).
The top one is threaded and a small strip of ply is bolted to it, for an easier grip when the bar is almost completely lowered, and again for centering of the bar.

[scratchbuilt_designs]

Added in total some 26.4 kg weight to the bed with the steel/epoxy infill, plus some stiffness and dampening improvement.
I am reasonably content with that...

[scratchbuilt_designs]

The machine bed is finished so far...

Rather than using flimsy zink casting angle blocks I preferred to make my own.
The mounting surface and location edge of the two linear rails were machined after the assembly of the frame to ensure a proper alignment...

[pippin88]

Great build (I've been following on Instagram)

I agree with your Z axis comments (moving carriages)
People often completely forget about the tool and too stick out and the need to get the tool over the top of the workpiece.

When analysing the Z axis only, moving rails Z axis may be slightly stiffer when the Z axis is fully raised, but only when the Z is fully raised (i.e. almost never) and to get the same workpiece clearance, requires a higher gantry which means less stiffness, all the time.

[scratchbuilt_designs]

Exactly. 100% agreed.

Moving rails are ok for people who use small spindles, like a Kress, AMB, or a Makita or Dewalt mini router which have to be clamped right at the end of the spindle (usually a Ø43mm flange) In order to lower such a combo down to the spoil board for cutting plywood sheets Z axes with moving rails have benefits, because they usually can be lowered completely.

But once you start with some Ø80mm Chinese spindles or even bigger stuff, moving rails are just bollocks...