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Thread: How NOT to make a T-nut
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28th Sep 2019, 10:33 PM #1Diamond Member
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How NOT to make a T-nut
So, I needed to make a T-nut to attach tooling on my Hercus lathe:
IMG_0099.jpg
Here are the steps I took, just so you don't repeat my mistakes
1. Pick a piece of steel plate/strap which is pre-drilled and tapped, to "save time!" Make sure you don't check how hard the steel is 2. Cut a bit off roughly the correct size: IMG_0098.jpg
Five minutes in the cut-off saw? Wheel must be blunt )
IMG_0100.jpg3. Realise that this steel is too hard to mill, file, cold-chisel, or generally do anything but grind.
Decide that a narrow cut-off wheel in an angle grinder is the way to go, because it will remove a minimum of material - should allow me to cut two slits instead of grinding the whole keyway out.
Clamp grinder to a surface plate with angle iron and packers as a guideIMG_0101.jpg
Precision ground die press tooling under the job. Closest thing to parallel blocks I have4. When it is starting to get dark, jump right in and start grinding.
What could go wrong?IMG_0102.jpgIMG_0103.jpgIMG_0104.jpg 5. The cut isn't going well. Is the steel really that tough?
No - the grinding disc isn't parallel to the surface plate.Didn't take a photo, but the slit is a different height on each side of the job. About 3mm across the 40mm. 6. Start afresh the next day. Measure twice, cut once? IMG_0106.jpg 7. Narrow cut-off wheels are surprisingly flexible.
This means hundreds of passes to try and recut & correct the angled slits, because the angle pushes the disc down or upIMG_0107.jpgIMG_0108.jpgIMG_0109.jpg 8. Find another spacer for the other cut.
Measure its height on one side only, because you are basically lazyIMG_0110.jpg 9. Jump right in and start cutting. Should be finished by lunch! IMG_0111.jpgIMG_0112.jpg 10. This little block of steel is getting too hot. Screw a threaded handle in IMG_0113.jpgIMG_0114.jpg 11. Inspect the cut. Height isn't quite right.
It looks like my spacer isn't parallel. More angled cuts.
Search for something else to use. Not going to finish before lunchIMG_0115.jpg 12. Start again with different spacer. Near end of cut, feed in from wrong side of wheel. It actually clears the removed material better. IMG_0116.jpg 13. After about 4 total hours, hold the hot job in my burning hands, and bolt it in before you can see the imperfections IMG_0118.jpgIMG_0119.jpg
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28th Sep 2019, 11:13 PM #2
I would have gave up long ago, drilled and tapped a new peice of steel I could mill.
Saying that did carbide not want to touch it?Using Tapatalk
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28th Sep 2019, 11:26 PM #3Most Valued Member
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Going by the sparks, I'd say that is a piece of tool steel or Bisalloy.
So much for a "quick" job, that's how most of my 5 minute jobs turn outTo grow old is mandatory, growing up is optional.
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29th Sep 2019, 08:41 AM #4Philomath in training
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Nigel, remember there are other members scattered around the country (and for that matter the world) who in the main don't mind helping others out. I'm assuming you ground the T nut because you did not have a mill. While it's satisfying to be able to say that you did it all yourself, a little job like that would be no problem for someone with the right gear. Much less frustration...
Michael
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29th Sep 2019, 03:52 PM #5Diamond Member
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Dave: Only have some old screw-in HSS end mill cutters.
(unless you count little Dremel style Carbide burrs and Diamond toys)
I could risk my factory neighbour's Carbide cutters, but would that be socially responsible?
KB: I'm guessing its Bisalloy. Probably the fixed block from a guillotine or shears.
Michael: Indeed. I'm still building up contacts.
Do have some people who could help, but wanted the satisfaction of doing it myself.
Also,
1. no suitable mild steel block was handy - still building up the scrap pile
2. correct assumption! Sold Dad's RongFu mill to a friend about 4 years ago.
(admittedly, it was a better drill press then mill)
3. factory neighbour offered a rod of 4140 to turn a big new bolt out of,
bit I wanted the satisfaction of doing it myself.
And it was a bit of fun learning, pretending I was a tool or die maker.
(who, from what I've seen, precision grind everything?)
P.S. Just for fun, here is what the slight tapered edge of a cutoff wheel does. On the other side of the wheel, it did automatic feeding!
Last edited by nigelpearson; 29th Sep 2019 at 04:16 PM. Reason: Add silly video clip
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30th Sep 2019, 10:26 PM #6
As Michael said, there are plenty of us out there that will help out, and you will probably get someone close by and willing to share info and ideas etc and learn more while you visit.
We all started somewhere, I only wish pre internet I had a mentor, I would have loved it instead of learning on my own.
On the other side, I can can see myself in my teens doing something like you have done, never say never has always been me, and nothing is too hard no matter how many hours it takes as long as it saves a few dollars and gets the job done, lol.
Dave JUsing Tapatalk
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