Hi Callum - bigger is always better in machine parts. Peter
Type: Posts; User: peteeng
Hi Callum - bigger is always better in machine parts. Peter
Hi G- so your using 40MPa as the modulus in your modelling? 40Mpa is its strength not the material stiffness. Metal posts with concrete around it means the concrete has shrunk onto the post... Peter
Actual no, the bond strength between steel and concrete is very low especially if its not prepared correctly. Which in the case of hollows. So when it disbonds you will have a 16N/um machine vs a...
Hi G - Be careful with "adding cement" the FE model has the cement bonded to the steel with 100% efficiency. In reality most "cements" shrink and over time will dis-bond from the steel. Then the...
Hi Craig - All of this is covered in the jerk thread I started elsewhere, very big subject. All I can say is that hobby level and lots of commercial level velocity planners are very crude in the...
Hi Craig - just because we have a trapezoidal velocity plan does not mean it is held to in reality. The path can overshoot, it can undershoot it can do several things depending on the motion planner...
Hi - There are two main modes of motion in a machine. Feeding and rapids. Rapids require large accelerations for commercial machines to reduce air time. Feeding speeds require constant velocity for...
Hi Stop - Buy a commercial printer that you can afford. They range from cheap to eye watering. Peter
Hi Momentz - Yes I've read you can't use the same rack. With straight rack you can. Thanks I'll send a note to the supplier to see If they have mirrored rack. Thanks for the heads up. The forum comes...
Hi Momentz - I'm currently going with the alignment method vs the spring drive. I think a little patience is worth the result. Good to know it works well once done. The rack is in 1.4m lengths so I...
Hi Momentz - I was going to use 5:1 gearboxes on this one. So that's good - Did you use a spring contact for the pinion or just mechanically aligned? Peter
Hi all you brains out there - I'm designing a 3mx1.5m rack and pinion router with helical rack and pinion drives. Any one done R&P before and have any words of wisdom? I'm nailing down the final...
Hi Callum - In the rail direction the ballscrew provides the axial rigidity as in the rail direction the bearings are compliant. So take a ballscrew thats D20 and 500mm long. Its stiffness is around...
Hi G - You can also apply 1um deflection to your part and the FE will figure out what the reaction is to achieve that deflection then no brains needed as then you know its N/um immediately... Peter
Hi G - X&Y Ballscrews are sized in a 3 step process. Because they do not lift mass (X&Y) they only need to move the inertia and the friction. Neglecting friction you need to pick a suitable...
Hi G - Here's a link to a BK dimension table. Plus FBT have all the other component dims as well. Peter
https://www.fbtmotion.com/html/12.html
Hi Callum - You are travelling down the right path. My suggestion is that you use plate for the whole structure and not use SHS or RHS. This gives you the ability to use the correct thickness as...
Hi G - Convert your results to N/um so we have common units to discuss. What load did you use? I'm sure all commercial FE systems will give the same result if given the same data and geometry. Peter...
Hi Well - I suggest you don't do half and mirror it. SW is not sensitive to that sort of issue. If you do half and mirror it you will have to be careful with the curve ends trajectory so ytou don't...
Hi G - I suggest you download one of the main manufactures catalogues and use their numbers. They have detailed dimensional data on their products. Hiwin skf INA etc they all build to international...
Hi G - Thats a local shear transfer tactic. Shear transfer and distribution is something I have had to learn about in this sort of machine design. Machine parts like to be thick. Peter
Hi G - Topological "optimisation" algorithms are generally based on removing low stressed material. This approach often does not develop high stiffness solutions. I can realise all of the weird...
To describe what's happening with Funkier 2 -
In general the AI has connected all the bearings (with all the other bearings) with ligaments that form triangles.
1) The saddle area is solid and...
Hi all - The generative design always wants to connect the Z axis to the base... So I tried the automated connection feature. Got this funky shape....Plus others Peter
edit added funkier 2
...
Hi Scott - Buy either round supported rails and suitable cars or square rail and suitable cars. By the time you buy bearings, bits of metal and lots of bolts to make your own linear bearing you will...
yes each section needs to be on a separate plane. Peter
Hi - I ran it thru the generative but it attached the Z axis to the bed. I did say make it as stiff as possible and I suppose that's the correct answer. I'll have to add some preventative material...
Hi G - I looked at the model closer and a couple of the cars still had balls. That would be the failure. Anywho I replaced the cars and rails with some dummy geometry and ran the optimiser. The...
Hello Kolias - The DM556 is a digital motor driver. You set the microsteps and the max current to suit the application. The driver does not do this. What it does do "automatically" is figure out how...
Hi G - I meshed your model. It had a few issues but was good enough to run, then the solver failed so I expect the mesh was poor in some spots. Simplify the cars and I can rerun it. Peter