Reply with QuoteOne nema 34 sprocket reducted With a chain drive will pull that x fine ThoseOriginally Posted by Jason Marsha
belt gear boxes look very expensive and bulky and there are two of them Why? thanks Tom
Belts or Chains
I am working on my second build I have a 50 x 100" bed on my first cnc
and I used sprockets and chains. I love them easy to work with smooth running and no backlash. I used the chain on the x because of the long run
and the extra weight of the gantry. Also you can easly use a sprocket reduction. check out sprockets and chains @ mcmaster and carr.
Thanks and good luck Tom
One nema 34 sprocket reducted With a chain drive will pull that x fine Those
belt gear boxes look very expensive and bulky and there are two of them Why? thanks Tom
Hey Tom,
One for each side of the Y axis which was originally going to be 10-12 feet long.
The third one (black) was for the X axis in the event I was going to make that axis the long one.
In terms of expense they each cost ~ $140.00 US dollars.
Jason
Jason I have a big x to pull on my build and I plan to use one nema 34 high tourque with a chain reduction to a cross gantry drive shaft It just seems like
you may be over tourqued. You could lift a house With your gearbox By the way nice work that stuf looks great Tom
A single belt may be used on the X axis with the 300 oz inch motor. We will see how it works out. The Y will carry two 5 start screws direct drive.
Jason
Y axis with 2 screws direct drive 2 motors tandem ??
I like your reduction drives I just think it might be to much you will be
turning that stepper fast to get to 100 ipm don't you think ?
Did you build those drives with parts from mcmaster carr for $140 ?
how much does y axis weigh Is there a lot of stiction on your rails ?
thanks Tom
Tom,
Pic shows how the machine in configured.
Two motors will move the gantry along the Y axis, up and down
One motor for the X axis. Left to right
With the belt drive the final output gear is 20 teeth 5mm pitch.
At 6.25 reduction one turn of my motor will move the axis 16mm or ~ 5/8"
100 ipm is no problem at all.
Y axis with gantry and router will weigh about 120 pounds.
Parts from SDP-SI & the Big Bearing Store. Bought some parts back in 2007-2008 prices may be different now.
There is some friction but it will loosen up quickly with probably an hour of machine usage.
As for the gear reduction drives they started as a scratch drawing and quickly evolved into the monsters they are today.
They would be much neater using aluminum with milled holes for the bearings to be pressed but Al is too expensive here in Barbados.
Thanks for the questions and observations I actually have the first gear reduction unit on my desk right now with fond memories of its assembly.
Jason
This is my latest build
This is one side of my latest build. So you can see why I'm interested in
what your building lota weight that one gantry end is 90 lbs overall this
side weighs about 400 lbs were gona have 5 axis with 3' Z
My two quality control technicians test the strength of the X axis.
One more piece of 100mm X 55mm I beam for the support is due to be fitted in addition to the three already in place.
The angle iron is 1/2", I figured if I placed it like that my V bearings would have maximum contact.
I have to brush off that surface rust and decide on paint colours.
I also have to figure out how to square up everything properly.
Jason
Last edited by Jason Marsha; 01-11-2013 at 06:26 AM.
More pics.
The long threaded rod is 10mm diameter turned down on a lathe to get a tight fit for the 3/8" bearing hole. I was still able to use the 10 mm nuts as much of the thread remains for a firm grip.
The bottom bolts are standard 3/8" bolts.
Jason
How close to parallel are the welded on angles?
They are welded at the edges of the I beam so if the I beam is perfectly parallel so are the angles.
We clamped straight pieces of metal past each edge of the I beam and then clamped the
angle up against that metal. There was a strip of wood with two 45 deg chamfers at
the top and two pieces for each side at the bottom that would force the angle against the metal strips.
It was a mess of clamps but it worked out well in the end.
Jason
I borrowed my Uncle's 6 foot level and got the machine squared and leveled up today. The floor was level already except for a small bump so I just had to fit a large washer under the right side of the machine and I was good to go. I will bolt on the gantry this weekend and fit on the Z axis just to see how it all looks.
Jason
Drilled 32 holes in the 'L' brackets on the drill press using a 3/8" DeWalt pilot point bit.
After bolting down the L brackets I used the same bit to start the holes on the gantry and used a cheaper black oxide bit to finish. Needless to say the cheap bit gave out after 16 holes.
Still need to drill 16 holes to finish but the sun is hot and I am tired.
Jason
Got motors mounted.
Hi Jason,
Your build is coming along great.I would like to see that monster move around.Give me a call when you are ready.(aka clammy23)
Good going jason, you're almost there, then you get to pick it all back down and paint it
Thanks Guys.
No I am not picking it back down to paint it!!!!!!
After the spectacular failure of my spinning nut design I fell back on my original belt drive design.
Assembled and tensioned the belt today. The movement is very smooth.
Finished the control box. It was a Dell C521 but after a bit of cutting with the angle grinder and banging with the hammer I got it done.
The three fans caused the board to shut down after about one minute. I disconnected the center fan and everything worked perfectly.
So I assumed that the current draw from the third fan was exceeding some predetermined limit. I then found another fan with half
current draw of the center fan and it continued to work perfectly.
Originally this was the fan setup
Fan #1 0.16A
Fan #2 0.17A
Fan #3 0.18A
After
Fan #1 0.16A
Fan #2 0.09A
Fan #3 0.18A
Photocopier transformer is giving me 38 volts at the board after rectification. I used the 26.5 volt 13 Amp setting.
I built a 8'x8' table for big cnc, it was supposed to be 12'x8' so maybe next time.
Screws (1/2" - 10 5 start) and motors mounted onto the machine, about to organize the cables. In order to allow for easy control box removal
I will be forced to used motor connectors.
The smaller machine with the holes in the gantry is a 4x4 assembled from parts I had on hand.
Jason
It is alive
I got the 5x5 running today after almost stripping the leadnuts. Reversed the Y and forgot to reverse the A Axis, the two ends of the gantry moving in opposite directions.
I wonder if the moderator can change the thread name to 5 x 5 instead of 5 x 10?
X axis : Belt Drive (6.25 to 1 gear reduction) top rapids in testing - 800 inches per minute, however 300 inches per minute is a more sensible rapid.
Y axis : Dual 1/2" - 10 5 Start ACME rod top rapids 300 inches per minute.
Z axis : 1/2" - 8 2 start ACME rod top rapids 300 inches per minute.
The 297 oz. inch 60 mm Sanyo Denki motors mounted on the X and Y & A axes that I salvaged from photocopiers are working great.
Low inductance of 2.4 mh as compared to the 6.8 mh for the Hobbycnc motor
The 305 oz. inch 56 mm Hobbycnc motor on the Z is also working well.
Some 2x4's for the plywood support and I am good to go. An all in one computer would be great, less stuff to lug inside after cutting.
Will post a video soon
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