Steel Blade Table Idea

[Tim Mellor]

So I have started looking at bed options for my upcoming 1290 Laser build. The usual suspects of Honeycomb and Aluminium blades are there but they have some strong negatives for small parts in the case of blades and gunk build up and back side marking with Honeycomb. I still might get a 900x600 Honeycomb for paper and cloth but apart from floppy items I can't see many benefits to using one. Combine the downsides with very expensive freight out of China and there is a good chunk of $ to play with to DIY a solution.

I have been largely happy with the Pin bed I made for my current small Laser but the solid surface tends to limit airflow a bit and across a 1000mm Bed would be worse. Like the Honeycomb I might still make a smaller pin bed section to drop in for some jobs.

So somewhere in my coffee fueled thoughts this morning I did a bit of Cad work and a concept model based on 1mm Steel interlocking blades. The plan would be to get them either Plasma or Laser cut locally then drop them off to a local Sand Blaster to smooth the cut edges.

1mm Plain Steel strips running at 50mm spacings. Slots at 1.2mm for clearance. Made in two panels (for easier removal or swapping out) of 930x700 would be 70 strips of steel for both sections.

Easy to knockdown into parts for cleaning if needed or replacing damaged blades if needed.

Thoughts?

[Tim Mellor]

Possible solution before there is a problem. I blame/thank @Gene for this one

3 printed riser with a brass nutsert fitted then a grubscrew and Domed nut. The bottom bit could also be made from steel or aluminium but 3D printing for a no bodge look

[Pete Cyr]

I think a flat top blade would be more practical - I dont see the advantage of a sharp peak i this application. If you were plasma cutting yes.
In this isnatnce I would presume most of the mateial you cut/engrave will be flat stock of some variety. Small stock with cutouts will have a tendiency to shift when cut oon this bed.

[Tim Mellor]

Like all things it is a compromise I guess. The Airflow advantages over a Solid base with pins is a pro and reducing the back side marking/cleaning problems of a honeycomb bed with the raised points goes somewhere toward the advantages of a pin bed. Being Steel magnets could keep stock in place if needed.

When I costed up the Aluminum ex China flat bar option it worked out to 1/2 the cost of a 100W tube and it doesn't solve small stock holding and being Aluminium you can't use magnets to help.

I can still see my self having different slide in or drop on bed options too.

Edit Tweaked the blades a bit to include some clearance fit locators for the V slot rails. Not shown is a strip to keep the blades in place along the bed. The points will be level with the V slot to allow for sheet location stops if needed. Two 750mm long banks to allow swapping out a 1/2 bed to something else.

[Tim Mellor]

Just for my own thoughts on the 50mm point spacing I dropped some virtual smaller stock onto the bed. 80x80mm 100x100mm and 80x900mm.

In one of my use cases these 80 or 100mm strips are going to be fairly common and be Balsa or maybe Ply blanks. Looking for a worst case the small blank still gets 5 points of contact and the 4" square hits 8. The question really is then will the Air assist or extraction move them I guess. Worst case is if you had a bunch of small bits to do just make a frame to hold them from getting moved by the air. In reality any blanks smaller than this are going to need a jig to hold them in place anyway and for 4" squares the number of point contacts should hold it flat.

[Neil Palmer]

Is there any chance you could post the design files for this as it is more or less what I have been looking for for a 1200 x 600 bed

Neil

[Tim Mellor]

Hi Neil, back to a PC tomorrow local time so I will sort something out then

[Gene Uselman]

Something else to consider is that it does not have to be uniform. My blade bed has had close spacing on one side of the bed and wide on the other since I set it up years ago. You can have the best of both worlds. I saw a plasma cutting table the other day with this style bed and saw a lot of possibilities. Easy job for a CNC punch press but a lot of machining otherwise. I am thinking now of how I could make small 'waves' in the sharp edge of my blades... hmmm.

[Tim Mellor]

True about the non uniformity bit. I had planned to do it in two halves so I could drop in a 900x600 Honeycomb or Vacuum table if needed. To save a few $ the other half could be even double spaced I guess.

Is there any chance you could post the design files for this as it is more or less what I have been looking for for a 1200 x 600 bed

Neil

Ok here is the link https://a360.co/300gHjT it is offered to ANYONE but strictly for non commercial use! You might want to check the 5mm tongue bits for clearance on your side rails and even tweak the origional to maybe 4.8 to make them an easier slide fit?

As it sounds like you will get to this earlier than me drop a few pictures back if you go ahead with it

[Neil Palmer]

Thanks Tim
I found that it was incredibly expensive to find anyone who would cut the pieces for me, being quoted well over 140 UK pounds to do the job plus materials, plus VAT at 20%.

That said I had been using a small bed on my K40 which was perforated sheet with "Punk Studs" screwed in. That had worked brilliantly with very little to none back scorching.
I decided to revisit that idea and after a lot of pricing up the options ended up with a 1200 x 600 piece, perforated with 3mm holes of 1mm mild steel. This was then scrubbed with coarse grit paper to reduce the chance of reflections and then 20mm pan head self tappers used at about 2" intervals.
Apart from a sore wrist from screwing in over 200 self tappers, you end up with a sturdy bed of nails with tiny points of contact.

Total cost for the perforated sheet £20 and then £25 for the self tappers. I had enough 2020 left to support the sheet and attach it to the motorised bed.

Pictures will follow in due course as it's apart again to replace a small tube cover that got damaged.

Thank you for the design, it really proved useful.