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Hi All - I often sight a stiffness chart to people here. But I have not been able to find where I got that snip from. Today I was looking for an article and came across it by accident! In "Metal...

correction Ante not anti

As long as you don't answer yourself back... you will calculate the logarithmic decrement.. Peter

Hi All - I've had a play with the column design. I made the arm 300mm high vs 250mm and this made the C frame a bit better. Although I feel with tweaking I could make the C frame same as the gantry...

Hi Pio - To stop littering your thread I have done a C frame to gantry face off in my Milli thread. I've had a small mill on the list for a couple of years but have been struggling with materials and...

Hi All - In another thread there has been debate over c column vs gantry style machines and various materials. I have made a comparison study to investigate this issue. Its a face off; raised moving...

Hi Craig - I'm not wedded to a particular config. Each config has its place same as each material has its place. Column mill designs are good for small Y axis machines so the table tends to be 2:1...

Thanks Craig - Looks like I read the wrong column (the VF-8 column). I have started shelling out Mill 1. Only lost a couple of um so far. But there's holes in the blocks so the shell is weird and...

Looking solid David - Peter

Hi Thomas - If you have a high speed camera you can image the cantilever damping. So support the beam on your nice steel table deflect a set distance and image the vibration / damping. Count how many...

Hi Thomas - One of their mixes claims E=80GPa. Give that a go. I expect in flexure it will be lower than the compression value. That would be interesting. I tried to get some shipped here some years...

Hi Thomas - The concrete chemist I worked with said that the bigger the aggregate the higher the modulus. We use a stone called blue metal here, mainly basalt. I don't understand why that would be....

Hi all - I had some time so upped the size of the gantry and the saddle and the Z plate. Got it to just under 11um which is close to 100N/um a good starting point. I think I should have modelled the...

Hi Craig - The next step would be to shell the parts until they came to reasonable weight with minimum stiffness penalty. It's a trade study and Round 1 so weight is not currently the main concern....

Good Morning PIO & Others - I've had a restless night going over my EG stuff. This morning Thomas published his bending test data on his EG and it came out at 22GPa. He has done very careful work on...

Hi Thomas - Good news. The numbers are in. Good to see they are the same order as mine. I've had a restless night thinking through the epoxy granite stuff actually. Come to the conclusion its...

Hi SP - I did correct the calculation so the attached prior is correct.. Cheers Peter

Hi Pio - For a trade study use simplified geometry, as simple as possible. The aim is to establish a direction. Your current model is nicely detailed nearly ready for manufacturing specifications......

Hi Vily - Yes the 400x200x16 is considerably stiffer globally then the 300x200 arrangement, plus the 16mm is stiffer locally and it has some meat in it for a machining allowance.... Since the big...

Hi SP - I'd suggest a 25mm belt but its miles stronger then required. I'd choose it for its stiffness. See attached calc. The 25mm wide AT10 belt has a rated load with 15t engaged at 1930N (well over...

Hi All- Great news! I have found a seller of flanged 50:1 harmonic drives. Saves making motor mounts and surface mounts. 20arcsec backlash very good. <$100USD per unit so cheaper than making the...

Hello Pio - I am not against concrete or any material. I pick the material for the job. If I were designing a large machine with integrated electricals and cooling, engineering grout CSA would be my...

Hi Vily - The external geometry is the same so why do this? Your only gain is in the two straps on the sides? Peter

Mr G-Spot - I won't get into various discussions with you in this thread or other threads. Unfortunately, what you say cannot be removed, it is unfounded. I have been designing & building machines...

Hi Pio:
1) thermal issues for a machine in a flat is unlikely to be a problem when aiming at a Hobby level machine. The principles of thermal symmetry if they can be applied is worthwhile especially...

Hi Craig - Garden fountains are a useful distraction. Peter

Ok - sounds like a good plan. Peter

So Vily - Do you intend stress relieving the weldments? This is best practice (and least risk for being able to machine the lands flat) and how are you going to machine the lands for the rails? The...

Hi Vily - I find using std SHS and RHS to be a limiting approach. But if your going to use it, select the biggest heaviest sections possible or combinations to create the biggest geometry possible....

Hi Vily - If any tool is not trammed then one side is higher than the other and will cut a scallop into the surface. The bigger the tool the bigger the error vs the same off axis amount. All tools...