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This is one of my zero backlash nuts. It has the same dimensions as a brass acme nut I used on my first machine. So I should be able to swap it straight out later.
(Getting the file sizes small enough is going to be a headache)
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Well I have been pondering the next machine I would build for quite some time.
I was thinking about a 1200x2400 work area but haven't got the room to build it at the moment. Thought I should build another hobby sized machine (600 x 1000 work area) and learn as much as possible to attack a bigger machine later.
My first machine was all MDF with acme thread, ground rod and linear bearings. That about blew the budget for a while so this machine has to be cheap.
The decision has been made that it will use cheap bearings on cold rolled steel for the linear ways and cheap threaded rod for the drive. I decided to try and allow for the threaded rod to be easily replaced with acme at a later date.
Work began early March
Have been taking pictures along the way but haven't posted anything until now as there was not a lot of progress to see and as my drawings are all on scraps of paper didn't want plea's for details.
Paul
This is one of my zero backlash nuts. It has the same dimensions as a brass acme nut I used on my first machine. So I should be able to swap it straight out later.
(Getting the file sizes small enough is going to be a headache)
These are my bearing trucks. They will run on 75 x 6 cold rolled steel.
Here are the bearing mounts and thread for the Z axis. The thread is 12mm. I don't have access to a lathe so the ends were ground down using an angle grinder and a jig and finished with a file and a drill to 8mm. An 8mm thread on one end will be used to lock thread in the bottom bearing. The stepper motor will drive the thread via a belt. The reasons for this are threefold. One it allows me to replace the screw easily at a later date and two it allows me to cantileaver the motor over the back of the unit. I am a bit worried that I may have too much weight possitioned forward of my y axis.
Thirdly If the stepping ratio is too much I can gear it up or down although I don't think this will be a problem on my z axis.
Z axis under way with the y axis bearing trucks in place. 8mm aluminium plate was cut on wood working saw so not the cleanest of cuts. I used a 60 tooth 10 inch blade and while it cut the aluminium ok the edge has a fine chisle look that I attribute to the blade melting the surface slightly. I wasn't prepared to buy a propper aluminium blade for the small amount of use it will get. I was initially using a saw table but switched to a drop saw as I felt a lot safer with the work well clamped down.
The z axis components in place.
The mount for the zero backlash nut connected.
The z axis steel plate connected to the mount.
A picture of the router sitting in the general area that it will be mounted in.
Interesting design. I like it, good job. Kind of like the torsion box designs only with steel. I see you are using the pressure plate thingy to keep the bearings in contact with the rails. It will be interesting to see how you attach to the gantry walls. I will keep watching.
It seems like a machine of this caliber/strength could use a multi start screw to kick up the speed.
Steve
Paul..
Please keep posting your progress. I am a newb to this area and watching the evolution of builds such as yours definately help me better understand the process and the mechanicals of designs. Maybe one day my confidence will be big enough to launch my own build.
Steven
Inspiring Thought for the Day:
Some people are like slinkies ... Not really good for anything....but they still bring a smile to your face when you push them down a flight of stairs.
The steel plate for the y axis will be screwed to a 40mm box section and this will be bolted to the gantry uprights. Bolted so I can assemble/disassemble and perhaps tune the hight above table if required.Originally Posted by spalm
Paul
Well it's been a while since I posted an update.
Things have been progressing very slowly. I haven't been able to spend as much time on the new build as I would have liked to but at least there is some progress.
I brought a cheap MIG/MAG welder and a CO2 bottle and regulator. My welds are not pretty. Just hope I have enough penetration on the welds. I've learned that CO2 as shield gas is not the easiest for a beginner. I recently found someone experienced in MAG and his tips have made a huge improvement in my welds.
I have used bolts on anything I may need to adjust. Hopefully I can shim any problem areas. Just finished a bit of paint today. Makes it look a lot better.
Here you can see the gantry being squared by adjusting the x axis bearings. The z axis mounted again after painting.
I'm quite pleased with how it moves. The bearings are running quite smoothly and it takes quite a bit of force to show any racking. I was thinking I may need to run two threads on the x axis but now I'm not sure. Think I will try a single screw in the centre. It should be fairly easy to move it to the side and add another it things don't work out.
Now the work will concentrate around driving the x and y.
Paul
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