can someone please help with hole dimensions

[reefy86]

above post mentioned tolerance stackup issue with tighter holes which is why i went back to 8.4mm. plate 2 was me trying to say i want a m8 cap screw to go through plate 1 and then screwed into plate 2 which is tapped ect. i apologise for my bad explinations. and machine cutting area is 8 x 4.

cheers

Ash

[Clive S]

above post mentioned tolerance stackup issue with tighter holes which is why i went back to 8.4mm. plate 2 was me trying to say i want a m8 cap screw to go through plate 1 and then screwed into plate 2 which is tapped ect. i apologise for my bad explinations. and machine cutting area is 8 x 4.

cheers

Ash

Have you put a drawing up about the machine gantry etc? Dean might be best to comment on plate thickness.

Bullet points are the best on separate lines to stop confusion when asking a question (just be blunt)

[reefy86]

just a quick one. if im using shoulder screws do i do the through holes 10mm which is what the shoulder screw is or do i make it slightly bigger like 10.1mm. dont want to make a mistake of inserting 10mm shoulder into 10mm hole and it gets stuck ect

[komatias]

Ok, shoulder bolts are ground to specific tolerances on the shank. Depending where you get them from, there will be a tolerance class to them like h8 or something. That will tell you what hole size and tolerance you should specify depending on the tightness of the fit you want. Give us a link to the bolts.

This is where geometric tolerance will also come in to play but that may be overkill for your application.


Are you looking to get this made by a chap in a shed or are a pro machine shop?

[reefy86]

just in general i was checking ebay out for the shoulder screws

http://www.ebay.co.uk/itm/10mm-M8-SO...DKYqt_xV0EeV8A

states nothing about tolerance just simple dimensions ect. although here it has more technical info but £3.44 per screw jesus lol.

http://www.shoulder-screws.co.uk/?gc...LnEaAskt8P8HAQ

[Boyan Silyavski]

just in general i was checking ebay out for the shoulder screws

http://www.ebay.co.uk/itm/10mm-M8-SO...DKYqt_xV0EeV8A

states nothing about tolerance just simple dimensions ect.

Ash

Shoulder screws are ground to specs, so a 12mm shaft shoulder screw is 12.00mm, see picture below. So i just drill a 12mm hole with a good new Dormer drill bit.

[reefy86]

thank you. just dont want to be making any mistakes in my drawings and want everything to bolt together nicely the first time.

Ash

[JAZZCNC]

Shoulder screws are ground to specs, so a 12mm shaft shoulder screw is 12.00mm, see picture below. So i just drill a 12mm hole with a good new Dormer drill bit.

You having a laugh.!! Drills are about much good at making accurate holes as I am at pole dancing.!! The whole point of Shoulder bolts is precision and this requires reamed holes.

I've not commented here because Ash has been in touch via email so I've told him this already but I'll repeat again here for the sake of others reading this who are just thinking about building.!

At DIY level building in lots of adjustment at the start is priceless when the machine built and your setting up chasing accuracy etc.
With all the best will in the world and careful marking etc there is point that without High precision machinery to help with build then your always going to need adjustment or wiggle room.
This doesn't mean high accuracy can't be achieved at DIY level it just takes lots of time and patience.