I am now running Version 21 of Gearwheel Designer and it gets better all the time.
I decided to make a ratchet wheel as my next test. This highlighted the need to think about the process order on the mill. Below is the design image in Gearwheel Designer.
My CNC sequence was as follows : –
Cut the square brass blank a little oversize and draw a diagonals on it to show the nominal centre (Manual operation).
Drill four holes in the corners outside of the working area of the cutting and use these holes to fasten down the blank to the milling table (which I had protected with a piece of MDF). (Manual operation)
With a drill bit as appropriate, drill radial holes in the centre of the spoke petals and also the centre hole.
Fasten the petals down to the MDF using these radial holes.
Cut the gash outline of the wheel.
Remove the four corner screws and remove the liberated brass outside the gash cut.
Cut the rough pass on the teeth.
Cut the fine cut on the teeth.
Fasten down the periphery of the wheel with small clamps.
Gash cut the spokes to leave the petals free from the blank.
Remove the screws holding the petals and remove the brass liberated.
Run the final cut on the spokes.
Job done apart from a light sanding to remove any small burrs.
Some more images follow : –
The purists will now tell me how it isn’t a proper wheel because the crossing interfaces to the rim have radius rather than a sharp corner.
Well a file will soon fix that …. and I can tell them how I watched another three episodes of House of Cards while this wheel was being cut.
Disclaimer : – This post and many others on my website feature references to Tormach and its products. I have no connection to Tormach Inc financially, commercially or otherwise. I acknowledge that Tormach®, Tormach Tooling System®, TTS® and PathPilot® are all registered trade marks of Tormach Inc.
My close friend in France also has a Sindoh 3DWOX DP200 3D printer. We bought them at a similar time. He has probably been a busier user of the machine. He has designed and making a very complex camera mount for tracking celestial objects. He is using an Arduino as the controller and has never written code before. He is having fun and keeping his brain stimulated.
A few weeks ago he reported that the raft that the machine was laying down before printing objects was not uniform and had ‘holes’ in it. The result was that the PLA being extruded for the object being printed, would droop down into the void in the raft and spoil the finish of the object while also making it hard to separate from the raft afterwards.
We swapped ideas remotely about what might be the cause and tried various tests and experiments but to no avail.
As it happened a few days ago we were travelling down into France and calling in to see him for lunch so I had a chance to see the problem first hand. More head scratching until …. I had the printer bed in my hand near the window and the sunlight caught the surface of the plastic laminated to the metal bed. My eye caught a slight bubble in the plastic surface where the adhesive bonding the plastic to the metal had presumably parted company. This was the problem ! The air bubble, small though it was, was causing a discontinuity in the bed temperature profile leading to the PLA not flowing from the nozzle correctly.
We ran a print and put the object on a different area of the bed where there was no bubbling or scratches and the raft and the print were good.
Had a bad day on Saturday. I was milling a small tooling plate on the PCNC440 and got distracted. Result was a coolant puddle migrating into the bottom of the Tormach keyboard followed by a broken Haimer tip. Doom and and major gloom. The keyboard was a write off as the fluid had got into the capacitive keyboard laminated sheets.
As it turned out a new keyboard was much cheaper to buy from Amazon than import another one from Tormach being only GBP6 and the Haimer tip while a bit more expensive was imported from Germany via Amazon.
I was in the process of trying to work out why the Z settings appeared to be changing while drilling the matrix of holes on the tooling plate. The drill bit length was still the same figure as entered in the offset tooling table but the hole depth had reduced. I think it might be the Tormach Tooling Collet not being fully seated into the spindle and it had jumped home. Having just installed a new air compressor for the Fog Buster and the tool changer, it could be the air pressure was a bit low and not fully opening the R8 collet. As soon as the new Haimer tip arrives I will get back to it.
While ‘off-air’ so to speak I have been doing some 3D modelling on Fusion 360 to create some home grown Christmas gifts for the kids. First one off is a customised napkin ring with a brass ring at each end. The exercise taught me how to form text around a circular body (thanks to John at NYC CNC for the demo video). Not very sexy but functional.
I struggled with cutting the brass rings and was about to design them out and go to all PLA when I had the idea to use the Kennedy Power Hacksaw like a bacon slicer to cut off thin circular shims of brass from a 2″ tube. It worked well, was more efficient on waste than parting off in the lathe and gave a consistently wide slice.
Next request is for customised wine bottle stoppers. Not sure wine bottles stay unfinished long enough in our house to justify this but let’s see what Fusion can deliver for the kids.
I came upon the Delph site and was excited at the possibility to cut clock wheels on the Tormach PCNC440 as this was one of my prime motivations for the purchase. Does anyone love crossing out wheels ?
Delph has been feeding me with updates to their code and it is starting to make sense what it is doing and I like it. Today I have run a wheel on slightly hybrid code (Delph plus my direct G Code hacks) and I am impressed so far.
The Delph code lets you design all manner of wheels for clock and other applications. You can define the style of the teeth, the crossings etc and you can drill or mill arrays of holes. You can also define the order of the machining processes. I bolted down a square of brass with corner holes holding it down – you can see the holes in the MDF below. Next I had the Tormach PCNC440 drill the three sets of holes in the blank, then cut the blank to circular size to match the teeth maximum diameter. In the picture the mill is cutting a rough cut first pass on the teeth using a 0.7mm carbide cutter. Next is the tooth fine second cut and then I can cut out the crossings which is what the five screws are for – holding down the petals that will become free once profiled.
All went well in the first rough pass on the teeth called a Gash Cut in the software. I was running at 4000 RPM and 5mm per minute and each tooth was taking 4 minutes with a slow 3mm lead in. The second finishing pass was much quicker and now only leaves the crossing out to run. As each petal of the crossing out is cut free , the screws shown above will keep the petal segments in place so there is no damage to the tooling. I have made some small clamps on the 3D printer to put around the outside of the teeth to keep the wheel in place and centre screw to hold once the petals are cut free.
What a feeling to complete it and thanks to Delph for their support in getting me there.