Joe's 1000x600x200 steel and aluminium router started

[Sterob]

Very nice gentlemen....I want to be able to do that when I grow up.

[Voicecoil]

I needed an HTD5 pulley for a project, this was a bit odd as it needed to be fixed to a spinning bearing housing rather than to a shaft so I decided to make one on the machine. I used the cambam trochoidal plugin for the roughing allowing the entire part to be milled with a 3mm endmill, took a bit longer but meant no tool change. Part was cut dry with air to clear chips, worked out really well.

Well done, nice bit of work that. BTW, how did you hold it whilst machining? Pieces like that where the finished part doesn't have a lot of thickness I always find a bit of a challenge to hold down rigid.

[devmonkey]

'Great minds' and all that.

Yesterday I used the CamBam trochoidal pocket plugin to cut out the teeth for a ratchet made from Jarrah hardwood. Conventional shallow cuts tend to take the corners off the teeth where the grain is tangential to the wheel so being able to do a 12mm depth of cut with a 2mm diameter tool is a bonus. I still had to redraw the original ratchet design (produced in Gearotic which will also draw HTD and many other pulleys for you) with rounded teeth to avoid some chipping. This cut used a two-flute straight cutter with a speed of 1000mm/min and a stepover of 0.15 (0.3mm) and the maximum 24000 rpm. This took about 25 minutes for the 110mm diameter wheel.

Attachment 28721

Very nice Kit! This was the first time I'd used trochoidal clearing, definitely a keeper for thin endmills in metal.

Now I have a question for you pulley experts. I need to make a very large 157 tooth 8m timing pulley ring that will be fitted to the perimeter of a winch drum. The pulley needs to be made of a ring of material ~25mm thick with an outer diameter of 400mm and inner of 340mm. It could be made from aluminium, SRBP, delrin or even hdpe.

Trouble is I don't want to waste a large piece of material just to make the ring, any ideas? I've even considered casting a blank in aluminium but I don't have a foundry. Are there any castable machineable urethanes that are strong enough for timing belt pulley teeth?

[Kitwn]

I'm well pleased with the trocho pocket plug-in, it's a major step forward in being able to make hardwood clock wheels sucessfully.

How are you designing the ring of teeth for the pulley? I have the Gearotic software which can create accurate timing pulleys in all sorts of formats. If you need help with that I can send you a PDF for importing into CamBam (that's another plug-in).

Well if you want to get into a new hobby that involves playing with fire, melting aluminium is easy. The YT video below gives you the idea. Use previously cast aluminium alloys (old water pumps from your friendly neighbourhood motor mender etc.) rather than cans or other scrap. Sawing off the bottom of an old fire extinguisher makes a good crucible. Getting a sucessful cast with it is another story however.

Not sure on the use of 2-part plastics for something this robust or how well they machine but one option to consider is to make a master in MDF with your CNC machine and then a silicone mold to cast the final pulley ring, or a blank for final machining. I've done a bit of this for arty stuff but not for engineering. You aren't going to buy from Australia but the Barnes site linked below has info on materials and how to use them. Similar stuff will be available in Pommieland.

https://www.barnes.com.au/

https://www.youtube.com/watch?v=lSoWxG30rb0

Good luck

Kit

[devmonkey]

I'm well pleased with the trocho pocket plug-in, it's a major step forward in being able to make hardwood clock wheels sucessfully.

How are you designing the ring of teeth for the pulley? I have the Gearotic software which can create accurate timing pulleys in all sorts of formats. If you need help with that I can send you a PDF for importing into CamBam (that's another plug-in).

Well if you want to get into a new hobby that involves playing with fire, melting aluminium is easy. The YT video below gives you the idea. Use previously cast aluminium alloys (old water pumps from your friendly neighbourhood motor mender etc.) rather than cans or other scrap. Sawing off the bottom of an old fire extinguisher makes a good crucible. Getting a sucessful cast with it is another story however.

Not sure on the use of 2-part plastics for something this robust or how well they machine but one option to consider is to make a master in MDF with your CNC machine and then a silicone mold to cast the final pulley ring, or a blank for final machining. I've done a bit of this for arty stuff but not for engineering. You aren't going to buy from Australia but the Barnes site linked below has info on materials and how to use them. Similar stuff will be available in Pommieland.

https://www.barnes.com.au/

https://www.youtube.com/watch?v=lSoWxG30rb0

Good luck

Kit

I use a free command line dxf generator that can generate all of the main timing pulley profiles, super simple.

I just cut an 8m test pulley in 10mm SRBP P1, if came out very nice and extremely strong teeth. I think I will use this material and laminate a few layers together then bolt through, it is pretty cheap stuff and locally available to me.

[Clive S]

I use a free command line dxf generator that can generate all of the main timing pulley profiles, super simple.

I just cut an 8m test pulley in 10mm SRBP P1, if came out very nice and extremely strong teeth. I think I will use this material and laminate a few layers together then bolt through, it is pretty cheap stuff and locally available to me.

That's cheating. Do you have a link for it.

[devmonkey]

That's cheating. Do you have a link for it.

Here you go, https://github.com/paulius-zubaviciu...file-generator

You need java to run it.

[devmonkey]

I made the large timing pulley I was proposing today, it is a 157 tooth HTD 8M (20mm belt) for a project, pulley is ~400mm diameter. It was made from 10mm SBRP with 3 laminations at the rim. Turned out fantastic. I used screwfix cyano to laminate, this makes a very strong joint which you cannot get apart. It will never the less be reinforced with a ring of M5 bolts.

[Voicecoil]

I made the large timing pulley I was proposing today, it is a 157 tooth HTD 8M (20mm belt) for a project, pulley is ~400mm diameter. It was made from 10mm SBRP with 3 laminations at the rim. Turned out fantastic. I used screwfix cyano to laminate, this makes a very strong joint which you cannot get apart. It will never the less be reinforced with a ring of M5 bolts.

What a monster? what's it for may I ask?

[devmonkey]

What a monster? what's it for may I ask?

It is for winching humans into the air attached to paragliders, this pulley forms one side of the winch drum and is driven at around 10kW by a 25kW BLDC motor under FOC control.