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I was finally able to pour a sample of Durcrete E80. Mixing this stuff by hand is a nightmare, even my electric handheld mixer was inadequate.
The sample is currently undergoing heat-treatment (48h...

I'm not sure it's very relevant to the actual topic, but here's some old pictures of the build.

It was my first build and certainly far from perfect. But it was designed for milling aluminium and...

The stiffness values from the THK catalog are for ballscrew nuts!
The stiffness of the screw itself is calculated from its root diameter, length, and how it's supported at both ends.

A...

Watch this:
https://www.youtube.com/watch?v=_XGF2FZUTms

Concrete for general construction has nothing to do with concrete for machine bases.
I think you are vastly underestimating the many potential issues when filling hollow steel structures with...

Hi Peter, that makes sense, thanks for explaining.

Today I tried making a small batch (2kg) of UHPC with the standard E45 recipe. It was a complete failure.
I mixed by hand and with the help of a...

I might be a bit late, but avoid if you can. Those IKO LM guides are old designs with 2 rows bearings. State of the art bearings are 4 rows in O arrangement for much better stiffness.
Even Hiwin HGR...

Seems like you know better than TBI themselves, so no point in arguing anymore.

I meant absolute pitch, I edited my previous message. The pitch consistency is what you get with ground screws, and...

Sorry but you have no idea what you are talking about.
I still can tell what is ground and what is not.


Also absolute pitch accuracy is not a big deal. The ballscrew can be mapped. The main...

I cannot disagree more. I've ordered a bunch of ballscrews over the years. All C5 or C3 ground. The last one I bought a couple of weeks ago was a TBI 1000mm 2005 C5 ground with custom end machining...

I think you should finalize your design before buying more random parts and trying to make them fit :)

But yes you can buy bars of Blanchard-ground steel and bolt them. This is my go-to supplier:...

This is exactly why you should NOT buy the cheapest Chinese servos, they are an exercise in frustration. The Delta ones have decent software and documentation.

Well there is simply no speed regulation. The actual spindle speed will vary with the load. And also the low torque below rated speed.

Peter,
I recommend avoiding these Chinese servos. For little...

I just didn't remember very well... My motor is rated at 3.2 Nm not 3.4 Nm, hence more confusion :)
I'll double-check next time.

I'm curious though what kind of VFD you'll be using. From my...

That sounds right. I missed the part where you said it's a 3.5kW motor. Mine is 5.5kW, hence the confusion.

Even if the torque is enough for some steel milling, you also have to keep in mind that...

I have one of these spindles. With the Chinese it's hard to get correct information. While asking for the torque/frequency curve of the motor I got 3 different replies, and their VFD settings were...

These are support units from SYK (Taiwan) and they are top notch. Exact same performance as THK/NSK ones for a fraction of the price.


Craig,
Again, there is nothing special about matched...

There is really nothing special about those bearings, they are just standard 7xxx bearings in P5 or P4 quality. The ridiculous price tag from THK/NSK doesn't mean anything.

Also these support...

Longer carriage: more balls, more load capacity, higher stiffness.
Flanged carriage: less tall, higher lateral stiffness.

So for machine tools you usually want to go with the longest flanged...

According to my sims a steel column will be about 50% stiffer than a UHPC (E45) column of the same volume and mass. But you're right that the steel one will be more expensive and requires more work.

Peter, thanks for all your advices.
Not sure what you mean by "restrain the cars at the arm" ?

I worked on sims all day long and overall stiffness seems to be "death by thousand cuts".
One...

No I'm in Europe. I can't find any settings to change my location...
If you want some Durigid I could send you some.

Yes the saddle needs work. However as is there is no issue with the carriage mounting bolts. First the saddle plate alone is bolted to the Y axis carriages, then the whole assembled table is laid on...

The above sims are obviously not a pure bending load since the base is fixed on 3 points with 2 of them directly below the column bearing surfaces. With a pure bending load the steel base is indeed...

Weird the pictures show up fine here. Let me try again.
502114 502116


I don't mind aluminium, but bolted designs are already a lot of work. If you need to add ribs everywhere it becomes...

This is the steel base (15mm plates, hollow) vs the UHPC one. Quick sim with 3000N on the column bearing surfaces.
Steel base is 132kg vs 120kg UHPC.
502110502112

About machining: the only machining allowed is the one I can do myself. I can use my previously built CNC with 640x500x250mm travels (a fixed gantry design, mainly designed for aluminium milling). It...

I also thought that steel had the best stiffness/weight performance for the base, and I tried making a steel base (simple box shape). I ended up with a heavier and less rigid result according to the...

Good question :)
I didn't think much about it, but I was thinking a beam supported on both ends, the load in the middle and a DTI measuring the deflection.
How would you do it?

Hi all,

I've been planning on building a small benchtop mill-drill, about the same size of a RF45.
Yes I know I could spend only $3000 and get a chinese RF45 clone, but I prefer starting from...