Reply with QuoteMove the Y rails to the back of the uprights, bringing the Z axis more in line with the X bearings.
First aluminium cnc build
Hi all,
I am planing to build me my second cnc machine from Aluminium. The first cnc was made out of mdf. Sadly because of move to another country I did not have any time to make parts with my old cnc for the second cnc.
Anyways before I starts I have couple questions. First of all what do you think from the design(picture 1). Some of the detail work is still not finished, but good enough to start building. The base frame is made from 45mmx90mm 8020 aluminium and rest of machine is made out of 15x30 8020 extrusions and extruded aluminium plates. Should I add more thickness somewhere? My plan is to use this machine mainly for wood and plastic.
Working area for this machine is around:
x 800mm 31"
y 600mm 24"
z 90mm 3 to 4"
My second worry is that the aluminium plates has to much tolerance for the build. Each aluminium plate has a tolerance of 0.008" in thickness.The problem is showed in attached picture 2.
-Juri
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Move the Y rails to the back of the uprights, bringing the Z axis more in line with the X bearings.
It was in the first place as you say, but to simplify the build I moved it as it is now.Originally Posted by Boomslang
Any comments on the aluminium plate thickness do you guess think it is enough? I am eager to order more parts...
ordered today all the aluplate parts from www.onlinemetals.com. Total cost including shipping 100$. I hope that the aluplates are strong enoght. Anyway I am hopefully that it will work and that I can start building next week.
Attached the order and ordered parts status in red.
My experience with larger aluminium plate (ie 1/4" and thicker) is that the thickness is very reliable, at least with pieces from the same sheet of metal.
I've never seen anything like 0.008" variation in thickness in a single piece of metal. Although I should say I normally buy good quality sheet in 6061, from a reputable manufacturer.
Aluminium arrived !
RomanLini as you said the 1/4" plate is very stable and does not bend easily and there seems not to be the variation what is was afraid of.
I started drilling the Y axis. The rails are attached by 5mm bolts and I dilled the aluminium by 7/32" drill to get 0.5mm adjustment. If you take account that the rail has an 6mm hole I am sure that I have enough gap to handle the tolerances.
I was surprised how easy the aluminum is to work with I was thinking it would be much harder. Attached some pictures of the progress. Hope to finish tomorrow rest of the Y axis and move to the Z.
Looks like you don’t have much respect for good furniture.
so long as he doesnt drag it along the top of the wood it should be ok :
A layer of cardboard would save the finish.
I hate that table and general quality of that table is horrible! So this will be its last use.
Last edited by Jur1; 01-30-2011 at 04:22 PM.
Finished today the y-slide. I noticed that I need more accurate when I start to build the Z.The IKo 9mm has more and smaller holes. I had some difficulties to fit the Y-slides to the aluminium plate. How accurate results can I get when I print the hole layout to paper and drill the holes based on that?
You can find attached pictures from today.
Bolts ordered
where did you order from?
I was thinkin to order the fasteners from Fastenal a local store but they sell the items in 25 or 100pcs. So I canceled the order. I am thiking to buy the the srews from McMaster-Carr
Can anybody say is this the right bolt to use with 8020 15 serie profiles? The neck seems to be quite high 0.1875"...
http://www.mcmaster.com/#carriage-bolts/=avqs2g
Can somebody tell what carriage bolt are you guys using with the 15 serie 8020 profiles?
If you model out the bolt from mcmaster it looks like the square part is to tall. See attached picture.
Last minute change to the plan. What to do you think if the sides would be changed from 15 serie profiles to . Is the material stiff enough? See attachments.
Last edited by Jur1; 02-06-2011 at 12:27 PM.
Rest of the parts ordered from cncrouterparts.com, mcmaster.com/ and 8020. Hopping that they will arrive before weekend. I am now 400$ poorer.
Changed also the design a little bit. The main frame is done now from 45x90mm aluprofile and the ends are 0,375 aluplate. Attached the image of new desing.
Received parts from cncrouterparts and mcmaster cart.
I will tomorrow finish the y and z axis. Started already today with the y axis.
Finaly had time to continue my build. Drilled the holes to CRT bars. The material was much softer that I excepted. Next I need to buy carriage bolts since I forgot them on my last order.
some ideas . . .
Looking good so far. I've built 2 cnc machines so hope I can offer some advice.
Base
The base in the latest dwg looks ok - are you putting legs under each corner to raise it up?
Gantry top
The gantry horizontal is just plate section which will twist more than other types of section when cutting in the X direction (longest axis). If this turns out to be a problem then a second plate on the rear of the gantry uprights, mirroring the front plate could be added with spacers to join the front and back plates together. This would be significantly stiffer for little weight gain.
Gantry sides
If you raise the bearing blocks on the X axis gantry sides so that they run on the top of the base instead of the bottom then the bending on the gantry sides would be less and there will be less deflection when cutting in the Y direction (short axis). You would need to add 1/4inch plate to the central member of the base to bring the level back up for mounting the work table on.
Just some thoughts, good luck with the rest of the build . . .
