Improved Z lower mount

If anyone is interested, I've just pushed an improved version of the Z lower mount to my GitHub repository. I decided to replace the countersunk screws with regular M4 x 12 cylinder head screws after I noticed that my original ABS part had broken:



I believe in general it's a bad idea to use countersunk screws exercising a lot of sideward pressure, because these parts apparently tend to break at the layer bonds. Well, but my improved part provides some additional space for M4 washers, so I think the holding forces can spread more evenly. I really don't believe this one is going to crack anytime soon

Good improvement! Yes, countersunk holes are generally not so good in printed parts. With ABS you can improve the strength by filling the countersunk hole with acetone, leave for 15-20 seconds then shake out all the excess. Leave overnight to completely dry out, and the layer bonds near the hole will be a lot stronger.

Dave

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zombiepantslol
..I believe in general it's a bad idea to use countersunk screws exercising a lot of sideward pressure, because these parts apparently tend to break at the layer bonds.

Absolutely agree, thanks for improving that!

Erik

I've been wanting to do the same thing with the ormerod 2 Y motor mount. There's a long countersunk groove allowing Y belt tensioning and mine has already started to split. Perhaps that will be my first attempt at part Editing!

James

nice work... will be adding this to my list or replacement parts

Excellent. I'd never thought to check this out but when i have looked you can see the layers splitting. Definately going to print this once i get some more filament
Thanks.
Just an FYI the cylinder head screws are called Cap Head Screw. Cylinder head screws are mostly associated with the automotive industry.

Great idea.As soon as I get my printer back up and running I am printing this first. I've had 2 of the original brackets split in the space of half an hour. Currently using a very bad bodge to fix

> Cylinder head screw
I make this mistake myself from time to time Zylinderkopfschraube is the literal german translation of the above.
while not being a a specialist in the matter I think the automotive part has the same german name

Thanks for your feedback - so it turns out I'm not the only one facing this issue

I'll keep in mind these screws are called cap head screws, I didn't know there was any difference betwen them - LEO doesn't even know that expression. Out of curiosity, is there any actual difference between cylinder head screws and cap head screws, or does it just depend on the area of application?

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zombiepantslol
Out of curiosity, is there any actual difference between cylinder head screws and cap head screws, or does it just depend on the area of application?

Cap head can be round while cyilnder head is well a cylinder?

The only cylinder heads I've worked on were all held with studs and nuts, so I don't believe I have ever seen a "cylinder head screw" :-)

Dave

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dmould
The only cylinder heads I've worked on were all held with studs and nuts, so I don't believe I have ever seen a "cylinder head screw" :-)

Dave

Some Fords (And prob other makes) use what looks like a CapHead screw but quite often have Splined drives similar to a Torx Screw.

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dougal1957

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dmould
The only cylinder heads I've worked on were all held with studs and nuts, so I don't believe I have ever seen a "cylinder head screw" :-)

Dave

Some Fords (And prob other makes) use what looks like a CapHead screw but quite often have Splined drives similar to a Torx Screw.

The last time I worked on a car to do anything more involved than change a wheel or bulb was about 40 years ago. I have noticed that they have changed out of all recognition these days and seem designed to prevent DIY maintenance - some even need special tools and significant disassembly to change a spark plug. Changing a headlight bulb in my present car is quite a business, and pretty much impossible to do in the dark.

Dave

Yes Dave you are right like in my current car it is a main dealer job to replace a Front Fog Light Bulb (Think the Bumper has to come off)

Doug