Coming along nicely, cut with a cut off wheel?
A plasma cutter would have been a lot easier but of course that's dependant on having access to one.
I have one in the shed and it's a pain dragging a compressor out to use it so I mostly use a grinder (see lazy). The plasma cutters are however fast and clean with minimal grind clean up.
Coming along nicely, cut with a cut off wheel?
A plasma cutter would have been a lot easier but of course that's dependant on having access to one.
I have one in the shed and it's a pain dragging a compressor out to use it so I mostly use a grinder (see lazy). The plasma cutters are however fast and clean with minimal grind clean up.
I burnt through a bunch of grinder discs until I ran out, turns out the hardware store has grinder discs specially for Ali, that made a world of difference.
I burnt through a bunch of grinder discs until I ran out, turns out the hardware store has grinder discs specially for Ali, that made a world of difference.
Yes, the regualr grinding/cutting wheels fill with swarf and can no longer maintain a grinding surface (same thing happens to files, keep a good wire brush handy to clear the teeth).
There are also better branded quality wheels than cheaper ones too (not suggesting you used cheap wheels).
It would have taken a while hand cutting the rims?
Got a fair bit done on the altitude trunions, machined flat and profiled ready for the next step. The chuck on the lathe was gripping the inside of the wheel so didn't have much gripping power...
This resulted in some lathe chatter on the outside edges as the harmonics of these were ringing like a bell. I am actually very happy with the chatter effect on the front side.
Next step is to machine out the center 5 stud holes and have one larger, better looking hole, then mounting them to the tube rings.
Quote:
Originally Posted by Leo.G
Yes, the regular grinding/cutting wheels fill with swarf and can no longer maintain a grinding surface (same thing happens to files, keep a good wire brush handy to clear the teeth).
There are also better branded quality wheels than cheaper ones too (not suggesting you used cheap wheels).
It would have taken a while hand cutting the rims?
Angle grinder with the right discs worked well once I finally bought some ali ones. It only took ages with regular steel discs as I had to keep changing them haha
That chatter gives the rims a rather unique finish, they look great.
What's the swing (over the bed) on the lathe?
It's a big machine. It wouldn't be the easiest turning job gripping the inner edges.
Saying that a local engineer is selling a turret lathe, the thing is 30 feet long or thereabouts (I forget) and he said he's had offers of $2,000. It comes with $40K+ worth of chucks and tooling, I'm going to need a bigger garden shed. My cheap Chinese thing I have cost me a lot more than $2K (currently up around $8K with tooling and compound table and vice for accompanying milling machine).
Mockup of my cannon wheels, I mean... altitude trunions. They look pretty good for rough start, still plenty of finishing work to do to get the final look a lot nicer.
Now that I have the trunions sized and mocked up I can get the measurements to make the rest of the Dob base.
Overall length is around 2300mm and very top heavy. I need to have the rocker box extraordinarily tall as the weight is all in the lens. It will be a very odd looking scope for those who are used to the bottom heavy nature of most Dobsonians.
Wow, I was thinking you had 5 stud tube rings.
You mentioned boring the centres, what diameter hole are you going for in your calculations?
Too close to the spokes will weaken the overall design.
Would you be better going to a hub design you bolt the already stud holes to the hub for overall strength (unless they have been machined down to a flat surface).
I guess you are trying to maintain strength while keeping mass down?
Still, it's an impressive machining job and no easy undertaking I'd assume?
My lathe wouldn't even do mini minor rims, 300mm swing over bed but 700mm between centres.
Sadly I studied fitting and machining as an aside to fabrication engineering along with hydraulics and pneumatics back in the late 90s and still had a lathe for maybe 10 years later that but had to get rid of it during an emergency move into emergency accommodation. (Cert 2 in each I think, Cert 3 in fab engineering, arc, MIG, Tig, Oxy and fabrication design and loadings, I honestly don't remember which certificate for the 3 nights per week for 2 years for machining and hyd/pneu and have no idea where my paperwork is, I have no need of the qualifications, I can't work anyway.
We now have our own little Chinese thing in a garden shed up the back yard which came as a kit with a bolt on milling machine but I didn't like that idea because it's very restricted functionality so I bought a nice compound table ($1,000) (ForestWest have some nice gear for good prices) and a good vice and had my engineer friend drill and tap the cast bed of the compound table (I hate tapping cast iron, don't mind welding it when I have the correct blow torch handy for pre and post heating (and an oven for the rods) but I hate tapping the stuff. He did a great job on it but now I have to weld up a table/stand for the machine and I'm confused with my dimensions. I was going to make it the full travel length of the compound table but that's not really necessary and I save a lot of materials with a more compact size. I have 40x40 SHS, 4mm wall thickness and I have some 50mm (or 75, I forget) c channel with a 6mm flange and I was going to put that across to mount the compound table and mill. The more rigid the build is the better the milling finishes.
My main problem is getting the steel to bend a swarf/coolant tray because I'd like to add a recirculating pump to the coolant and eventually convert it to a CNC unit. No trailer or ute and delivery of a 1200x2400mm sheet is rather expensive.
That takes brains and money, I'm short of one and thin on the other, lol.
I really need to get it done soon. The lathe weighs 300 KG (small unit) and is standing firm on a stand I welded up (thankfully, I over engineer everything for strength, part of formerly being a forklift technician and car hoist specialist/technician over the years.
It's going to be a very interesting build when you get it all finished!
