2024-03-10

Last modified: 2024-03-10 14:41:23

Machine design

Fastener requirements are:

• BK12: 4x M6, max. head diameter 10mm, through 30mm, into Minerva with 6mm pocket, inserts required
• Ballnut holder: 4x M5, through Minerva with 11mm pocket, into 16mm thread
• Ballnut: 6x M5, through 10mm ballnut, into 14mm thread
• HGR15: M4 fasteners already supplied, inserts required
• Carriages: 4x M4, through Minerva, into 10mm thread
• Spindle clamp: ???
• Frame bolts: ???

For each fastener I need to decide on head type, thread length, whether I need a collar/washer type thing. And for each insert I need to decide what type and what length.

So preliminary bolts are:

• BK12: normal M6, 30+25-6 = 49mm max. length, need >30mm, <49mm (qty 12)
• Ballnut holder: flanged button head M5, 16+25-11 = 30mm max. length, need >14mm, <30mm (qty 12)
• Ballnut: normal M5, 10+14 = 24mm max. length, need >10mm, <24mm (qty 18)
• HGR15: (M4x16mm already supplied)
• Carriages: flanged button head M4, 25+10 = 35mm max. length, need >25mm, <35mm (qty 48)
• Spindle clamp: ???
• Frame bolts: ???

But! For the flanged button head bolts (the ones going through Minerva), probably want a counterbore for the head so that the surface can stay flush. So they'll need to be shorter by the depth of the pocket, which needs to be deeper than the height of the head.

I expect I can hold the spindle clamp with bolts I already have in stock, will just maybe want to buy some extra M6 inserts.

And for frame bolts, maybe M8? I might be able to use the M8 flanged button head bolts I already have, may need to acquire more.

And threaded inserts are:

• BK12: M6, max. 14mm long
• HGR15: M4, max. 25mm long
• Spindle clamp: ???
• Frame bolts: ???

I'm keen to get quality inserts, mainly need to make sure they are steel instead of zinc. I don't think the installation method is too important as I'll be epoxying them anyway.

"Threaded sleeve" looks to be the ideal type. Has a round exterior so I'll just drill a hole and glue it straight in.

I couldn't get M6 sleeves as short as 14mm, so I've gone for 30mm length and intend to cut them in half on the bandsaw, and perhaps finish on the lathe if they're still too long.