[How do I?] Set up to mill a to cut long 45 deg chamfer

B

bob12345

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Hi all,

As I'm still pretty green on the mill, I thought I would ask you fine people first.

I need to cut a few dozen t-nuts for some 2020 slotted aluminium extrusion, I know I can buy them in steel for pence (cents) but I want some in aluminium for weight saving reasons.

Most of it is pretty obvious, mill off the top to dimension, mark out some holes then drill and tap, cut off to length on the bandsaw, but can I can't work out how to efficiently put the chamfer on the bottom of the part on a long piece of stock without a tilting head or tilting mill vice or a 45deg chamfer bit (none of which I own)?

I'm trying to avoid adding to the "bought for just one job" draw, but even if I just pony up and buy the endmill, work holding still looks difficult, if I chamfer first, how to I hold the part for the milling and drilling, mill first, how to I hold the part to cut the chamfer?




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You can stick the length in the t-slot groove on the table. Put the piece whatever angle you want and clamp it down to the table with holdown clamps. Leave your head alone and cut your pieces.
 
Since there is nothing critical about tapped hole location, I would do ALL of the work before cutting the pieces apart. Mill the top step, drill & tap the holes, hold the bar in the vise as shown in the end view to mill one chamfer, flip over and mill the other chamfer, then cut into individual nuts. Leave the ends saw cut or belt sand to cleanup. If you want a better finish on the ends, hold the nuts vertically in the vise and use an endmill to finish. For the chamfers, I would recommend you put a little money into a facemill that uses sekt/seht inserts. Chamfers are the least of what they are good for. Something like this one


It will need an FMB22 shank. The shank style will depend on your mill and preference.
 
Or……you could bypass the whole silly mess that those t nuts and go with t bolts. Like these:

www.ebay.com

DCT | 5 Star Knobs Kit 5/16”-18 Threaded Knob Bolt with Knob Jig Knobs 4-Pack | eBay

The possibilities are endless! Warning: This product contains chemicals known to the state of California to cause cancer and birth defects or other reproductive harm.
www.ebay.com

personally I hate those silly t nuts precisely because of the 45 deg chamfer. It certainly doesn’t need to be as deep as they cut them. It makes them sink so low in the slot and go cockeyed where you can’t start a bolt in them. If you’re not ever taking them an apart, ok. But my application I use my 80/20 as a reconfigurable jig table and until I went with those t bolts and knobs it was a stupid mess with having to stick a skinny screwdriver underneath the t nut to get it unschwangled so I could put a bolt it it. IMHO the stock t nuts are not worth copying exactly. Rant off….I feel better…
 
MrWhoopee said:
Since there is nothing critical about tapped hole location, I would do ALL of the work before cutting the pieces apart. Mill the top step, drill & tap the holes, hold the bar in the vise as shown in the end view to mill one chamfer, flip over and mill the other chamfer, then cut into individual nuts. Leave the ends saw cut or belt sand to cleanup. If you want a better finish on the ends, hold the nuts vertically in the vise and use an endmill to finish. For the chamfers, I would recommend you put a little money into a facemill that uses sekt/seht inserts. Chamfers are the least of what they are good for. Something like this one


It will need an FMB22 shank. The shank style will depend on your mill and preference.
Click to expand...
Thanks, that does look like the most effective way, thanks very much.
 
C-Bag said:
Or……you could bypass the whole silly mess that those t nuts and go with t bolts. Like these:

www.ebay.com

DCT | 5 Star Knobs Kit 5/16”-18 Threaded Knob Bolt with Knob Jig Knobs 4-Pack | eBay

The possibilities are endless! Warning: This product contains chemicals known to the state of California to cause cancer and birth defects or other reproductive harm.
www.ebay.com

personally I hate those silly t nuts precisely because of the 45 deg chamfer. It certainly doesn’t need to be as deep as they cut them. It makes them sink so low in the slot and go cockeyed where you can’t start a bolt in them. If you’re not ever taking them an apart, ok. But my application I use my 80/20 as a reconfigurable jig table and until I went with those t bolts and knobs it was a stupid mess with having to stick a skinny screwdriver underneath the t nut to get it unschwangled so I could put a bolt it it. IMHO the stock t nuts are not worth copying exactly. Rant off….I feel better…
Click to expand...
I'm not a fan of them either, but this is purely an exercise in weight saving, they are intended to hold a linear rail and a brace bar on a reasonably fast moving 3d printer, the standard are the post install spring ball nuts, not sure if you have seen thise before, bit clunky, but you can also drop them in and out of the rail.

Spring Ball Nut
 
Cadillac said:
You can stick the length in the t-slot groove on the table. Put the piece whatever angle you want and clamp it down to the table with holdown clamps. Leave your head alone and cut your pieces.
Click to expand...
That's a great idea, I did also wonder about just buying a small length of hex stock and just splitting it down the middle on the bandsaw, I think it would still fit in the groove.
 
Use the flat nuts from 80/20 . No need for the angle .
 
mmcmdl said:
Use the flat nuts from 80/20 . No need for the angle .
Click to expand...
I did consider just a flat "square" nut, but would that be the best type for a rapidly moving part, I kind of dismissed them as they just looked a bit weaker and loose in the slot, where the traditional one looked a bit more locked in?

But I guess there will be around a dozen of them spread over the length
 
80/20 nuts pull into the aluminum and don't move . I would suggest you investigate what they have and sell .
 
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