Reply with QuoteHi giz,
Good to have you along, and hope we can keep the interest fired.
I will start on the aluminum parts Tuesday if all goes well. I will post pictures of the parts as I get them cut.
Are you planning a 5th axis build or something else?
following this build closely - very interested in your work so far!
Hi giz,
Good to have you along, and hope we can keep the interest fired.
I will start on the aluminum parts Tuesday if all goes well. I will post pictures of the parts as I get them cut.
Are you planning a 5th axis build or something else?
Regards,
Wes
Looking forward to the results. This site has something equivalent:
http://www.nexengroup.com/nxn/produc...ails/id/966551
I would think that laser cutting would not be accurate enough and it would be best to use CNC milling method. The above site has CAD drawings in case you want to use CNC milling methods.
Anyway, some day I will start on my own 5th axis project using the trunion method.
That Nexen group stuff would be nice although a 1m section of it is like 516 bucks. Not to mention the pinion is another 502. That would make for a very expencive setup. Unfortunate they are not compeditive (price wise) with rack/pinion
b
Hello again,
I got around to cutting the backplate for the 5th axis head today. I ended up using .125" 5052 aluminum instead of .25" so I made some changes to the part shape and decided to form the flange on the squared end as .125" does not give much material to drill and tap or rivet to. Here is a picture of the part as finished. I have a lot of other parts to make to get this mechanism tested, but this is a good start. Take a look and I always value your input!
Regards,
Wes
Do you have any 3d renderings of the finished product?Originally Posted by metalworkz
Great to see you're getting stuck straight into it Wes
This is just a cut and paste from my build log.......but I think it's good to add this thread to have as much info regarding BC head in the one place as possible!
Well it has been some time since posting as I've been on Holiday in Thailand.
I have made some good progress since my return.
You will be pleased to know that the BC axis are now fully assembled with the Spindle mounted also
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You have no idea....well you probably do, how happy I am to finally see this thing together:rainfro:
Hello Liam,
I just got back from your build thread and was admiring your machine.
Your 5th axis turned out great and with a streamlined appearance to boot! I know my build will not approach yours in style or performance but I will be happy if it at least functions properly. I can always work on improvements to the design but this mechanism has to be tested first.
Keep at it and we'll be watching to see the next installment to your build.
Regards,
Wes
Hello diyengineer,
Sorry, I don't have any 3d models of the 5th axis design. I started to draw some of the parts in Sketchup but only finished the original back-plate in a 2 piece design for .25" aluminum. I sure would like to get the Alibre design software and start doing more things in 3d, and they have had some great deals lately but I was not able to take advantage of it. What do you use for your 3d moleling and drawing software?
Regards,
Wes
I use solidworks 2010.
Below is a machine i was going to build until a better option arose. Fully modeled and a million renderigns. You can see it evolve from nothing to something fairly fast depending on the input of a lot of smart people
http://cnczone.com/forums/showthread.php?t=100925
If you want to shoot me any 2D drawings i can make them 3D for you and render them as well? It would help to get a feel for the entire thing. feel free to send me what you like, just make sure everything is dimensioned out, and the 2D parts have notes on how thick there suppose to be. My email is my username @gmail.com
=)
Keep up the good work!
Hello,
I used a makeshift idea to form the .125" aluminum back-plate in my 12 ton hydraulic press today. The results are not as good as I normally expect but the part is usable for the prototype even with a minor cosmetic blemish at the bend. One small step down and more to come as I work my way towards finishing the parts and assembling them all for a test. Here are some pictures to look at until there is more progress to post.
Last edited by metalworkz; 09-16-2010 at 06:39 PM.
Regards,
Wes
So far this looks amazing! do you have access to a welder? Instead of bending and being stuck with any kind of radius you could of cut the piece and welded it 90 degrees to the surface. Its looking good so far! Keep up the good work!
Hello,
I did another small task today with the B/C head assembly parts and got the bearing retainer plates fabricated and assemble to locate the main bearing for the head. I dimpled the thinner aluminum with the 12 ton press for the inside retainer and used a thicker flat plate on the outside surface. This was less work than boring a plate and I think it took less time. The finished retainers worked very well.
Regards,
Wes
Hello,
I did do some more work with the 5th axis parts today. I did not accomplish as much as I had planned but I did get a couple of things done. I made a .25" thick 6061 aluminum set screw boss for the sprocket and mounted it and I also made a .375" OD x .25" ID sleeve adapter for the pinion wheel so I will fit on a .25" dia. shaft motor.
It took longer than I had figured and looks like so little was done but I guess it is one more step out of the way. Still a lot to do to get to a trial assembly stage. I also have spent some time to draw the cover side for the drive and will need to get that cut asap. I tried to get a shot of the edge view of the drive to show what has been done.
Regards,
Wes
Someone mentioned earlier something about the use of timing belt to turn a harmonic drive. This actually sounds like something worth trying. I currently have a NEMA 34 906 oz stepper and I was thinking of using a timing belt, and a 1:1 ratio from motor to Harmonic drive which would reduce it to a fine resolution without backlash. The nice feature I see here is that the ratio is adjustable via the belt gearing. Now I need to know what gearing I should go with for the harmonic drive? Right now I have 1.8 deg/step and 906 oz-in of torque. I'm hoping the holding torque will be sufficient for the b axis. I Know this sounds bulky but I plan to build slow and big and adjustable.
Hi Blazed,
You should probably work backwards from the resolution you would like given the distance from tool tip to center of rotation of your design.
900 0z-in sounds like heaps of grunt! I'd like to know more about your application?
here is a post from me earleir in thread if you need a hand to get your head around it.
"Scenario
Say you have a distance of 200mm from center of rotation to tool tip and 8:1 reduction, This gives you a circumferance of 1256mm, divided by 200 fullsteps = 6.28mm per step, divided by your ratio 8 = 0.785mm per step.
This may be adequate with micro stepping, from what I've read positioning of micro steps are no way near as accurate as the positioning of full steps.
The thing is I don't think you really need much more than 1 full rotation of your axis per second, in this scenario thats a feed rate of a whopping 1256mm per second
An 8:1 reduction will give 1 rotation per second for every 1000rpm of your stepper, you'll be able to run steppers much higher as you multiplying the torque also.
Can you add a layshaft for a second reduction stage?
keep in mind you'll be able to reduce the size of the existing 8:1 pulley.
How about two 5:1 reductions give a total of 25:1
resolution of 0.25mm before micro stepping
0.66 of a rotation per second at 1000rpm of stepper
Assuming a 400 oz in stepper, An output range of 52 ft/lbs at 0rpm and 4.6 ft/lbs at 2000rpm ( which would only happen during rapids, not cutting)"
hope this helps, BTW my harmonic drives are 50:1 and if I was to do over I would belt drive them like you have mentioned for better packaging of the B/C assembly.
Cheers Liam.
any new updates? your progress is looking good so far - and like MoN said, I too like the idea of keeping the spindle underneath the z-axis.
I've been going back and forth on whether I should do a high-z 3-axis or simply go for the 5-axis. I'm leaning toward the 5-axis, though I see myself just going the Doughty Drive route.
Hello Giz,
I have not done much with the 5th axis parts lately, but I did work on the drawing for the top cover side for it. I have it ready to cut but the mill is currently being used to make a wood pattern for a motorcycle side case and I need to finish the pattern and make some castings before I can get back to the 5th axis parts. I attached the shot of the top cover side, and hope to get back on these parts soon.
Regards,
Wes
I going to be scouring ebay everyday for suitable harmonic drives to hopefully build my own B/C head.
The doughty drive is just too much $$ for what it is.
I've been doing that for a couple months now. They get spendy really quick, and I have been sniped on every auction I have entered in to
