Mechanics

dren-dk edited this page Oct 25, 2011 · 17 revisions

The buildlog.net 2.x laser (aka. bln2) seems like a good source of inspiration, even though it's a bit on the small side: http://www.buildlog.net/blog/2011/02/buildlog-net-2-x-laser/

The guy (bdring) who made the bln2 laser and runs buildlog.net has made a linear slide profile called MakerSlide and it looks awesome, I want it, bad.

The MakerSlide store has just about all the special mechanical parts we need at fair prices, so unless the shipping costs are unreasonable, it looks like that's our main source of parts.

The only trick is that bdring will not be taking orders until 22/10 at the earliest so we have to figure out something to occupy us util then.

A solution to the lack of MakerSlide profile might be to go the old route of using steel-rails, the price of unhardened steel isn't too bad (144 DKK a meter) so that would do nicely and at 720 DKK in total including moms, it would probably be hard to beat the shipping on MS.

Specs:

  • Width: 1800 mm: The chassis must be 1800 mm wide to accommodate the laser tube, but it can't be any wider or it will not fit in the CNC room.
  • Depth: 800 mm: The door to the CNC room is 800 mm, so the machine cannot be any wider than this.

The chassis of the machine will be built out of either 30x30 or 20x20 mm MayTec aluminum profiles and it will look a lot like the bln2.

To further optimize the depth utilization and to protect the tube, it might be a good idea to stack the tube on top of the chassis, in a separate compartment, with an acrylic front, that will also give a safe place to put a current meter (behind the acrylic to ensure that a faulty shunt resistor doesn't expose the user to 35000 Volt).

Airflow and compartments

To keep the laser and the electronics protected from fumes and fires I'd like to keep the cutting compartment separate from the electronics compartment and keep a higher pressure in the electronics and laser compartment than the room and the cutting compartment.

The air enters the electronics compartment via a filter and a 120mm fan, from there it flows into the laser compartment and out into the cutting compartment via the small hole the photons use, that should ensure that the small fan will always be able to keep a higher pressure, even when the exhaust fan is running.

To keep the machine clean (it sits in the dirty room), the fan will probably get a separate PSU with no off switch.

Framing profile use

The over all measurements of the machine will be:

  • Width: 1.9 m (Limited by the room)
  • Height: 0.4 m (should be plenty)
  • Depth: 0.8 m (Limited by the door)
  • Laser compartment height (l): 0.15 m

The bln2 laser is a good template to use, so if we stick to the basic template we'll need the following parts from MayTec:

In the 20 mm system:

Profile MayTec code Formula Meters 6m profiles Price (EUR/6m) Price (EUR)
20x20 mm 4H,LP 1.10.020020.43LP.60 12*W + 4*H + 10*D + 4l 32.5 m 6 29.6 178
20x40 mm 6H,LP 1.10.020040.64LP.60 2*W + 2*D 5.5 m 1 50.10 50.10
Total (EUR) 356

Parts needed for the integrated connectors:

Description MayTec code Price
76 connectors 1.20.2H0 167
Drill jig 1.99.01012 78.63
9.2 mm Ø drill 1.99.03109452 25.03
Total (EUR) 270

This is quite expensive, so a good alternative could be to simply cut an M8 thread into the ends of the profiles and cross-drill with an 8mm drill and countersink the head of a screw, this is more work and less flexible.

The second alternative is to use angle connections (1.46.204.1720.1HH) which cost 2.65 EUR apiece, bringing the total to 202 EUR, they don't look as appealing, but they are quick and easy to mount.

In the 30 mm system:

Profile MayTec code Formula Meters 6m profiles Price (EUR/6m) Price (EUR)
30x30 mm 4F,LP 1.11.030030.43LP.60 12*W + 4*H + 10*D + 4l 32.5 m 6 49.5 297
30x60 mm 6F,LP 1.11.030060.64LP.60 2*W + 2*D 5.5 m 1 92.60 92.60
Screws for connections 1.21.VSFM14 76 79.2 79.2
Total (EUR) 462

MayTec alternatives

Profiles Connectors Profile cost Connector cost Total cost
20mm Internal 356 270 626
20mm Angle 356 202 558
30mm Internal 390 270 660
30mm Screw 390 79 469
30mm Angle 390 202 592

Other than the raw chassis we also need some threaded plate to be able to mount stuff to it, we'll use MayTec 1.31.HM5 which is an M5 threaded plate with a spring for holding it in place.

Suppliers

Maytec

So far the best supplier of aluminum profile seems to be: http://www.maytec.de/ their danish representation is: http://www.tecnordic.dk/

The profile prices are online here: http://www.maytec.org/_neue_daten/sites/download/preislisten/files/2009/PL-1-2009-E-Euro.pdf

Igus

Igus has some cable chains that look like they might do the job: http://www.igus.dk/wpck/default.aspx?pagename=overview_EasyChain

Klee

Klee, has all sorts of nice looking V-groove bearings and guides, toothed belts and related hardware: http://www.klee.dk/catalog/group/nodeid/hepcosimpl

buildlog.net/cnc_laser

With the crazy high prices of legitimate linear bearings the kits page on buildlog.net is starting to look very attractive, using those parts would mean using a NMEA17 motor for the x-axis, but we have plenty of those, so that's ok: http://www.buildlog.net/cnc_laser/store/2x_kits_and_parts.php

Mobra

Mobra has toothed belts and pulleys, but not a whole lot more: http://mobra.biz/sw/frontend/show.asp?parent=151030&layout=0

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