Joe's 1000x600x200 steel and aluminium router started

I just looked up the hiwin specs, they say 130um over 500mm max allowable surface height error between two rails in the same plane, so I think this equates to an angle of 0.015 degrees or 53 arcseconds, I would be around 4x that with the rails mounted directly to the first slot. It would probably be absolutely fine but anyway.

I've made up some feet from spare plate. These are bolted into the bottom of the extrusion and will then be clamped to my milling table.

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I've just trammed the head to the table, and checked the table over the entire X travel. The table is within 0.01mm, i.e. I can't measure any error with a 0.01mm resolution DTI. Think i'm just going to flycut the top and bottom of the entire extrusion, then I'll have the option of mounting to a slot or tapping into the centre. No time to do it today taking the kids to see the new star wars film this afternoon.

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Originally Posted by devmonkey

another option is just to mill a few mm each side of the slot so the rail can sit flat, this would also preserve the 3 planar points (both corners and centre) in case I mess up.

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That's likely not such a bad idea as it could give some lateral stabilit - Hiwin suggest sitting the rails in such a groove in the manual. However you'll need to do it accurately as it removes the option for tweaking alignment to some extent.

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.Then again the centre of this extrusion will be stiffer than either slot as it i supported equally whereas the slots are supported on one side by the unsupported corner. No idea really.

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Routercnc's point about using a tapped strip rather than individual floating nuts might help this.

Well I've milled 4mm either side of the slot flat on each side of the extrusion. Setup took a long time making sure everything was flat with the dial indicator, nipping up the gibs to try and counter the sag from the long overhang. I pretty pleased with the result, seems at least as flat as the extrusion. I need to get some rails mounted to it and make the Y bearing plates so I can see if it is sufficiently parallel to be usable. DOC was about 0.25mm with a carbide endmill, could feel it was cutting deeper on the outside due to the increased slope as discussed in the previous posts.

I had to make the cut in two steps, moving the beam and refixing between cuts since the mill table wasn't long enough. I can see the transition but cannot feel it. Nice hatch marks show the head was in tram.

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Nice work, hope it sorts it.

I agree with voicecoil. My only suggestion when you cut the other one would be to support that overhang with an elastic luggage strap from the roof of your shed.

Kit

Hi Kit, I cut them both in one sitting yesterday, i measured the effect of the sag over the saddle with a DTI 4mm offset from the spindle (I used an 8mm endmill for the facing operation) whilst lifting the weight of the overhanging part, didn't really have any effect with the gibs tight as you would expect given the table pivots on the saddle. Probably not an acceptable way to fly cut but with a small endmill it works. I thought about slinging the overhang to my engine hoist but the problem with that would have been as the table is moved to the other end you would need to reverse the force since it becomes overbalanced the other side.

I think the best possible way to balance a job like this is to put a sliding counter weight inside the extrusion and move it through as the work moves (in the opposite direction), but I couldn't be bothered in this instance, if I was using the large fly cutter I would have had to bother else it would have cut a tapered scallop in the top surface.

Interesting :)

Milled the Y bearing plates, just need to counter bore them. Lower plate wraps around the rails on the Z front plate to reduce coolant splash up inside the Z assembly, it is also recessed to accept the rear Z plate press fit so that it is easy to line it up with the upper Y plate. The row of 4 holes that will be used to bolt the lower Y to the rear Z plate are undersized as I want to use them as a drill guide for the tapped holes in the rear Z. The Z is too tall to stand on my mill so these will have to be drilled on the pillar drill or with the cordless.

Also the spindle mount arrived from Canada, very nice bit of kit.
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Got the rails mounted on the milled gantry, worked really well. I've tightened them down but not yet aligned straight, for that I will mill up a couple of precision setting tools.

I then finished the Y bearing plates and bolted everything together. Everything slides very smoothly with bolts tight, very exciting! The Y bearings have the same smooth action across the entire length with no hint of any variation so I presume the gantry milling was sufficiently parallel.

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One thing I need to do before too long is hit the corners of these plates with a sander, they are razor sharp and I keep bleeding all over the lovely shiny parts.

Happy new year everyone!

Small progress update, I have finished the gantry end plates and X bearing plates.

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I have about 6 small plates to make for stepper and bk mounts then finished with the manual milling.