MK1 Steel router build log 1500x800x200

[Clive S]

Like your good ol bolts or tougher machine bolt style.

Does one need high tensile strenght?

Just standard cap heads black or zinc etc.

Cutwell do good taps.

[routercnc]

8.8 means tensile strength of ~800 MPa and yield strength of ~80% of this

12.9 means tensile strength of ~12 MPa and yield strength of ~90% of this

So 12.9 will be much stronger than 8.8 but you are usually not interested in that. You are unlikely to create forces high enough to break the bolts on a diy machine. 8.8 MPa is quite a lot !

What you are interested in is the stiffness of the bolts as this tells you how much deflection you will get when machining parts. But this will be similar in both bolt types so 8.8 will be fine. No harm in using 12.9 but they won't give you any benefit.

If you are interested in why it is because the stress/strain curves have the same slope, it is just that the 12.9 bolts will go further along the curve as they are stronger.

If you buy stainless there is a different naming system as stainless does not really yield before it breaks (by comparison) but again there is no diy CNC advantage other than looks nice and won't rust

[Nr1madman]

Hello!

How wide is the epoxy supposed to be?
Do you know that the sides tend to get raised, usually called meniscus?
I don't know if having the sides angled like that will lessen or make the meniscus worse..
Maybe you know something that we others don't and your solution solves the problem?

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[driftspin]

Hello!

How wide is the epoxy supposed to be?
Do you know that the sides tend to get raised, usually called meniscus?
I don't know if having the sides angled like that will lessen or make the meniscus worse..
Maybe you know something that we others don't and your solution solves the problem?

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Hi Nr1madman....

More knowledge? No.


The witdh of the profile is about 80 mm.
The witdh at 5 mm epoxy thickness should be about 70mm, plenty of room for some meniscus and enough flat surface left for mounting the rail.


I want to see what te result will be on the bottom of the gantry x mounting surface.


I might decide i want the wide type carriages on x because there is space enough for them there.. miniscus might become a problem there..

Any thoughts?

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[Nr1madman]

I'm sure you are right about having enough room left. Just concerned that the inwards angled sides will create larger miniscus. It might work the other way also :D

I have been known to be wrong! ;)

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[driftspin]

I'm sure you are right about having enough room left. Just concerned that the inwards angled sides will create larger miniscus. It might work the other way also :D

I have been known to be wrong! ;)

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Nr1madman.. Ha yes about being wrong... been there done that



I think you might be right about minicus getting worse when walls lean inward...


Will report on this...


I can still change stuff...
you know what i will.


On the x carriage mounting surface.. this is the spot where extra room is needed...

Grtz..

Bert



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[Nr1madman]

Nr1madman.. Ha yes about being wrong... been there done that



I think you might be right about minicus getting worse when walls lean inward...


Will report on this...


I can still change stuff...
you know what i will.


On the x carriage mounting surface.. this is the spot where extra room is needed...

Grtz..

Bert



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If the meniscus should interfere with wide bearings then it's very easy to file the meniscus down. Im just worried that there will be much waste as the epoxy is quite expensive :D

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[driftspin]

If the meniscus should interfere with wide bearings then it's very easy to file the meniscus down. Im just worried that there will be much waste as the epoxy is quite expensive :D

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yes its expensive... some 75 euros for +/- 3kg.. its cheapest i could find with good properties and tropical hardner...

need to put a heater in the shop because of this now

grtz Bert

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[driftspin]

Ok 1st pouring round.

I prepped 0.5 kg of epoxy.

Mix is 135 vs 365 expoy.


And yes.. in the first round i found out epoxy leaks through everywhere.


Goodthing.. acryl kit can stop epoxy leaks .


I made good use of the leaked epoxy by coating all surfaces of the next round... with a bit of luck i will have no problems there...

The 2nd round will be some 2.0 kg.

last round 0.4 kg.



I have made a decision on the Linear parts bom list today... i will order wide carriages for the x axis.


Fred: i will be ordering soon :-)

Hope to have the parts this year.

Lots of new things to think about!

Do you guys have any clue for how long i need to keep the temperature @20+ C for curing epoxy evenly?


Maybe 4 days or so?

Grtz

Bert.

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[Nr1madman]

Hmm do you think doing a small pour last will help making it level? I think bigger mass in the pour may help make it flow even.. I would do the 2kg pour last ;)

But you might be right, just an observation!

The curing time will depend on the epoxy used and thickness of the pour.. I was scared so I waited 10 days haha

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