Firstly I would like to thank all the people on this forum for the immense amount of detailed information being discussed, without which I could never have designed and made this Sled, this post is some part of repaying all the help. I started designing things some weeks ago after getting an update from Maslow that the second batch of kits were nearing readiness .
I looked at routers available in the U.K. and like many did not find much which appealed. Somebody on the forums mentioned brushless spindles from China so I started to investigate these, there are many available from 500w to many kW’s for a surprisingly low price. At this point a thought about doing light routing with a Bosch Colt which can quit easily cut 6mm MDF in one pass with a 1/4" bit), but the Colt is only 600W so I decided to start out with a modest 500W spindle as I read that the Maslow works best on shallow cuts. I will now describe the Sled and give details of it’s construction. It was modeled in CAD before making (TurboCad).
Let’s start with some pictures (saves me a few thousand words?)
I have uploaded a copy of the Cad Model to Fusion 360 (I have only just started using it). http://a360.co/2z8kn7o
So the sled has a 10mm steel base plate (on 9mm ply), a top mount pantograph and a 500w Brushless spindle on a Z mount. The total weight is about 13Kg (28 Lbs) and it is 500mm in diameter.
Spindle and Z Mount
The spindle is this kit from BangGood
The Z axis is made from this kit of parts
The 12mm hardwood plywood parts were drilled using a template printed from CAD, which worked out accurately enough the whole thing worked 1st time. The rails and lead screw are cut down to about 200mm which gives a Z travel of 75mm. The standard Maslow Z motor drives the lead screw via a GT2 Timing belt, which is tensioned with a spring and roller. The whole axis is mounted to the base with metal angle brackets and M3 bolts. The lead screw has a 4 starts on a 2mm pitch so advances 8mm per rotation, this should speed up the Z movement.
As I havn’t got a Maslow kit yet the Z motor is not currently attached.
The complete Z axis and Spindle was about £130 [$175) (Including the 48v PSU).
Main body of sled is welded from 2 pieces of 180mm wide 10mm thick steel (bits I had in stock) into a T shape, which was then circularised with a plasma cutter. It was after I had cut it out that I finalised the pantograph design which need more room at the top so the Spindle has been mounted below the center of the circular steel. A piece of 9mm Hardwood ply was cut to 500mm circle (up from 450mm to accommodate the change of center), this is bolted to the steel with 3 M3 bolts. The ply has pockets cut to fit over the mounting hardware to give a smooth base.
The Spindle was mounted then used to drill a center hole. After the pantograph parts were drilled a 50mm hole was cut in the center with a 20mm wide channel leading down to a 25mm circle for dust extraction. There will be a acrylic disc with a 20mm hole in it covering the large hole to allow viewing of the cut. There is a 22mm right angle plumbing fitting to connect a short length of 25mm vacuum hose which will connect to the dust extractor.
I have been following the long thread on Sled modification with great interest and decided to use the top mount type on my sled. I have followed @dlang design idea but have added 2 extra arms which will stay straight with the chain but will provide a easy sled detachment point with the Hand knobs (and no fancy shaping needed for chain clearance). The parts are cut from 5mm mild steel (a bit crude as I only had 50mm strip on hand and had to slice it up) and I plan to paint them. The vertical linkages had the bottom hole drilled then they were bolted to the sled center hole and the other two holes drilled through all 3 parts.
They are mounted to the sled with a M8 connector nut bolted from below with a short M8 screw, then the arms bolted down from above with a M8 bolt and lock nut to set the pivot. The rest of the pivots are just cut down 40mm M8 bolts with lots of washers. the Hand knobs are M6 and the bolts will be fixed to the main arms.
Now I just have to wait for the Maslow kit to come (Has anybody from the 2 batch had theirs yet?). I have designed a electronics enclosure with all the parts including a Raspberry PI and Touch screen but that’s another post along with the frame design (pivoted from the ceiling).
I hope this post will help other people and please ask any questions, though it’s all theory until I get my kit…