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Bevel Beveling T-slots after resurfacing table

itsmeBernie

Hot Rolled
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Jul 2, 2005
Location
Northern New Jersey
This info request should probably be in "General Discussion" as it would pertain to any machine, but here goes.

I got very lucky, and "made an offer" on an already inexpensive 42 inch Bridgeport table which was for sale locally.
It looked MUCH better than my current table in the photos, but in person, I realized I was VERY lucky. Someone had already begun work on resurfacing the table. It had been blanchard ground, to the best of my knowledge, looking at the very large radius grinding marks, approximately 18 to 24 inches or so. I will try to post pics that show them. Please correct me if I am wrong (after I get the pics posted in a few minutes). After measuring my current table, and a table of my friend, It appears this one had about .030 taken off of it at some point, or it was made years apart and to slightly different specs.

My Question is what would be a way, without another much larger milling machine at hand, to grind or cut the bevels at the edges of the T-slots again? I know I could just file them by hand, but I thought it would be nice to machine them properly. Maybe it makes no difference.
I already brought it to a friend who refurbishes machinery professionally to go over it for flatness etc, and it is really close to flat. It is also within .001 for thickness from end to end. It just needs scraping in, which he will do. It just saves me money to have some of this type of work done before he has to touch it.

I did a LOT of searching here and elsewhere for threads about this already, but if anyone knows of a thread that this is covered already, please let me know. I may have been a dimwad searching for it.

Thank You for any advice or direction

Bernie


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Just run a file or a de-burring tool over them. You only need to remove burrs to the point where they won't cut you when you use the machine. Any more is not all that useful.

I took 10 thou off both the top and the bottom of my 48"x10" milling machine table with a Biax. Count yourself lucky :D.
 
I built a wooden holder for a #92 plane. It holds the plane blade at 45 degrees at a specific height. The bevel is cut by adjusting the wooden holder so that the plane blade cuts deeper and deeper until the 45 degree surface is the width I want. The same thing can be done with a file, then a stone. It would look perfect and all edges would match.

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DSC_0957.jpg
 
Just run a file or a de-burring tool over them. You only need to remove burrs to the point where they won't cut you when you use the machine. Any more is not all that useful.

I took 10 thou off both the top and the bottom of my 48"x10" milling machine table with a Biax. Count yourself lucky :D.

That is a thought, Mark. I have some pretty ugly files which would actually give quite a bite if I wanted to. Maybe would be a more of an even finish than I am thinking. Just didn’t know if there was a trick for this, since I’ve seen some of the tables beveled pretty deeply.



Bernie
 
I built a wooden holder for a #92 plane. It holds the plane blade at 45 degrees at a specific height. The bevel is cut by adjusting the wooden holder so that the plane blade cuts deeper and deeper until the 45 degree surface is the width I want. The same thing can be done with a file, then a stone. It would look perfect and all edges would match.

View attachment 229211

View attachment 229212

Thank you Rons,
I like the idea of something like this, as it would guide a consistent angled cut. Maybe I could just make one that would take one of my big shaper bits, and I could feed it in a little at a time.. hmmmm



Bernie
 
This is where knowing somebody with a small planing machine is very useful. Failing that you're really left with a good 2nd cut file and emery cloth.

I hope I'm not bragging but if I filed that table you'd think it would have been machined when I finished. After 50 years you get good at the hand skills, I've also got the worn joints to prove it.

I recently had a bone scan regarding an operation I was due to have. When they gave me the results I had wear in every joint from the ankles upwards. Even the one that don't hurt me at the moment.

Regards Tyrone.
 
I made up this tool to chamfer the underside of the slots, something similar would work on the top.
Here's a link to the thread with other good ideas - http://www.practicalmachinist.com/vb/general/setup-reduction-t-slot-back-chamfering-tool-158329/?highlight=slot
We use a laminate trimmer with a carbide chamfer bit to deburr saw cut blanks. Maybe one with a speed control to reduce the speed would work on iron?

4017d1211075538-setup-reduction-t-slot-back-chamfering-tool-dscn8658-1024.jpg
 
One of the strengths of a Bridgeport is that the turret rotates left and right . . . this lets the spindle operate well left or right of the table center. In other words, use the rotation of the turret and the extension of the overarm to reach any part of your table with spindle tooling. Should not take over a couple of hours to chamfor / bottom chamfor all of the tee slots and table edges. Use your machine!
 
I recently had a bone scan regarding an operation I was due to have. When they gave me the results I had wear in every joint from the ankles upwards. Even the one that don't hurt me at the moment.

Regards Tyrone.

Sounds like the toes are still good then. No slacking, we'll make some slippers with file tang receptacles.

More seriously, I hope recovery is going well. Getting old sucks, but...
 
Sounds like the toes are still good then. No slacking, we'll make some slippers with file tang receptacles.

More seriously, I hope recovery is going well. Getting old sucks, but...

Thanks for that, yeah the toes are great, never been better. I don't get gout but a pal of mine does. Not recommended I believe. It hurts if you breathe on his toes when it's bad. Too much red wine I think.

If I lived a few thousand miles nearer I'd come over and file that table. Maybe I'm a sad old guy but I always got a lot of pleasure from a good bit of filing.

Regards Tyrone.
 
It’s nice when the bevel is accurately machined to the axis, so a shaft can be layed in the tee slot. Years ago when I had my Rockwell table redone, Rich at Garden State mentioned that he had done this on my table, but it didn’t really penetrate until a couple years later when I had need to do it.
Certainly not a requirement tho
Keith


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I made up this tool to chamfer the underside of the slots, something similar would work on the top.
Here's a link to the thread with other good ideas - http://www.practicalmachinist.com/vb/general/setup-reduction-t-slot-back-chamfering-tool-158329/?highlight=slot
We use a laminate trimmer with a carbide chamfer bit to deburr saw cut blanks. Maybe one with a speed control to reduce the speed would work on iron?

Thanks Mud.. I thought of something like the laminate trimmer or router with a carbide bit. I do have a speed control like you mention. I wonder if I would be worse with a trimmer or router than using a file and stone as mentioned.. Maybe if I mount it to a wide piece of aluminum I would be less likely to put divots along the way hah hah..
I like your tool with the bit. I might do something like this, on a larger block I can get both hands on, with a big HSS shaper bit instead, so I can't break it.
 
Thanks JR
I am starting to think I should just do it this way- I have a selection of really nice files, with various "bite"s.. I would avoid mishandling a router and digging out a chunk.
 
Thanks for that, yeah the toes are great, never been better. I don't get gout but a pal of mine does. Not recommended I believe. It hurts if you breathe on his toes when it's bad. Too much red wine I think.

If I lived a few thousand miles nearer I'd come over and file that table. Maybe I'm a sad old guy but I always got a lot of pleasure from a good bit of filing.

Regards Tyrone.

I am not afraid of a filing job, I actually enjoy it. I have a nice selection (COLLection hah hah) of files, but I sometimes make the mistake of taking a year and a day with a project that could take me much less time, surrounded by powertools and machines.

It is sounding more and more like I should grab an ugly file, and fine file, and some type of clamp to hold them at a consistent angle, and go at it. I just want it to look like I did NOT do this by hand, since it was originally done by machine at the factory.
 
Thanks JR
I am starting to think I should just do it this way- I have a selection of really nice files, with various "bite"s.. I would avoid mishandling a router and digging out a chunk.

Keeping the bevel even all the way along it's length and the angle the same plus keeping each of the bevels the same as the others is were you need the hand skills. I'm not saying it's rocket science but you need to have had a fair amount of filing practice under your belt.

With a good keen second cut file and some emery cloth you shouldn't need more than a morning to do the job

Regards Tyrone.
 
Keeping the bevel even all the way along it's length and the angle the same plus keeping each of the bevels the same as the others is were you need the hand skills. I'm not saying it's rocket science but you need to have had a fair amount of filing practice under your belt.

With a good keen second cut file and some emery cloth you shouldn't need more than a morning to do the job

Regards Tyrone.

If you want to get a little fancier, and have a better chance of maintaining a uniform bevel along the T nut slots, after some filing you can paint the bevel with a Sharpie, then take a ~1" square x 5-6" long section of Al bar, wrap some coarse sandpaper around it, then (holding at 45 degrees to the slot) rub it along the length of the chamfer. It'll show you where you're still high (no Sharpie) and help with uniformity when you're done.

In truth, it's good to have a bevel on the interior of the slot too, as that helps prevent nicks from T nuts closing up the groove. You can do some work here with a carefully applied file, then some folded up sandpaper as a final cleanup. If you want to avoid scarring up the bottom of the slot, cut a thin section of Al sheet the width of the T, slide it along while you're filing to act as a barrier.
 
Keeping the bevel even all the way along it's length and the angle the same plus keeping each of the bevels the same as the others is were you need the hand skills. I'm not saying it's rocket science but you need to have had a fair amount of filing practice under your belt.

With a good keen second cut file and some emery cloth you shouldn't need more than a morning to do the job

Regards Tyrone.

Keeping the bevel consistent along the whole length of the table is exactly my goal.



Bernie
 








 
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