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View Full Version : How Would You Countersink This???



JoeLee
04-22-2015, 02:07 PM
I need to come up with a way to countersink a couple holes inside this piece of cut out rectangular tube for the FHSC screw. With out making some special cutter or modifying an existing dovetail cutter, I'm at a loss. The inside width is .750. Other ways would be to simply notch the back out to allow access of a counter sink, so give me some other ideas?????

JL..............

http://i911.photobucket.com/albums/ac317/JoeLee09/Box%20Bracket/Image003_zpsaopvvjzm.jpg (http://s911.photobucket.com/user/JoeLee09/media/Box%20Bracket/Image003_zpsaopvvjzm.jpg.html)

Rosco-P
04-22-2015, 02:13 PM
With something similar to a back spotfacing tool: http://www.cogsdill.com/pdf/USCatalogs/CompleteCatalogs/USFlipcutBrochure.pdf

Mtw fdu
04-22-2015, 02:14 PM
Can you get in there with a die grinder?

Just a thought.

Mtw fdu.

Boostinjdm
04-22-2015, 02:31 PM
Grind a cutting edge on screw. Stick screw through hole and mount in cordless drill. Spin and pull.


Or make an access hole on opposite side of tube. You may want that anyway for tightening the screw.

Paul Alciatore
04-22-2015, 02:41 PM
I like the cutting edge on a screw idea. You could use a grade 5 or grade 8 screw and it should last for a bunch of holes in aluminum.

Another idea would be to drill the holes somewhat large and use the next larger size, flat head screw PRESSED in with a purpose made clamp. Again, use a grade 5 or grade 8 screw for your tool. You will need a good back up block with a matching hole in it to support the outside surface. This would go fast if you have a lot of them to do.

I suggest using a screw that is a size larger so you can bring the counter sink down to the level of the inner surface or even a bit below it. That way the final size screw will not protrude above that surface.




Grind a cutting edge on screw. Stick screw through hole and mount in cordless drill. Spin and pull.


Or make an access hole on opposite side of tube. You may want that anyway for tightening the screw.

SGW
04-22-2015, 03:07 PM
Make a countersink out of drill rod with a removable head that screws onto the arbor such that the cutting teeth are "up." The teeth don't have to be all that great. You can mill or file them to shape before hardening. Put the head in the slot, feed the arbor through the hole, screw it into the countersink, and pull the countersink into the hole (while it's turning, obviously).

I've made a couple reverse-spotfacers like this. It's not particularly difficult. Just be sure to make the teeth cut in the correct direction.

Doozer
04-22-2015, 03:24 PM
Ask the engineer who designed the bloody thing.

-Doozer

EddyCurr
04-22-2015, 04:53 PM
How many holes? How many lineal feet of channel?

A thought that has not been mentioned is to add a
second triangular 'filler' piece. Countersink the face
of the triangle's hypotenuse.

Edit: The filler piece would not necessarily need to
be the full length of the channel. Just make a number
of segments - say an inch long each and install as
required.

.

JoeLee
04-22-2015, 04:54 PM
Grind a cutting edge on screw. Stick screw through hole and mount in cordless drill. Spin and pull.


Or make an access hole on opposite side of tube. You may want that anyway for tightening the screw. This is what I thought of doing, but not too sure what the cutting edge should look like on the screw.

JL..............

Rosco-P
04-22-2015, 05:00 PM
It would look just like the cutting edge of a countersink. One or more cutting edges, flutes, relief, etc., except the shank would be on the nose instead of behind the head of the countersink.

Hawkeye
04-22-2015, 05:06 PM
Would something like these work for you?
http://www.travers.com/noga-reversible-deburring-tools?Category=UserSearch=debur||UserSearch=block id 87808 and class level3 id 297907

Yondering
04-22-2015, 05:18 PM
Ask the engineer who designed the bloody thing.

-Doozer

My thoughts too. Of course a lot of engineers (and I are one) these days couldn't tell you the difference between a drill bit and a countersink anyways, so it may not have been considered.

Rosco-P
04-22-2015, 05:33 PM
Would something like these work for you?
http://www.travers.com/noga-reversible-deburring-tools?Category=UserSearch=debur||UserSearch=block id 87808 and class level3 id 297907

For deburring, not for countersinking.

JoeCB
04-22-2015, 05:35 PM
engineers !!! ya' and I are one too. Why countersunk? Pure cosmetic or does the inside of the channel have to be clear? By the time you countersink for full depth of the head , there will ne scat material left to hold on to. Perhaps, better with an angled washer and a button head socket screw.

Joe B

garyhlucas
04-22-2015, 06:05 PM
It is very easy to design a very expensive part!

vpt
04-22-2015, 06:08 PM
Drill the threw hole, insert the countersink bit, grab it from the back side and spin.

JoeLee
04-22-2015, 06:12 PM
I only need to do two holes......... this isn't a production job. They need to be contersunk for clearance purposes, not cosmetic.
I see that there are some different types of tooling out there for this exact application, I like the one with the flip out blade but like I said I only need to do two holes. Perhaps I can slot a screw with my dremel and make it look like a countersink, that was my original thought prior to starting this post.

JL................

EddyCurr
04-22-2015, 06:26 PM
I only need to do two holes...Using the triangular filler piece (or angled washer, as JoeCB
describes what I think is the same idea), you'd be done now.

No worries about breaking through the wall of the channel.
No need to make a special tool. Adequate thickness to
retain use of the FHSC screws.

.

Rosco-P
04-22-2015, 06:27 PM
I only need to do two holes......... this isn't a production job. They need to be contersunk for clearance purposes, not cosmetic.
I see that there are some different types of tooling out there for this exact application, I like the one with the flip out blade but like I said I only need to do two holes. Perhaps I can slot a screw with my dremel and make it look like a countersink, that was my original thought prior to starting this post.

JL................

For it to cut, it has to have clearance, like a drill.
Can you use smaller fasteners and maybe more fasteners? A smaller head would use a smaller countersink, maybe it could be squeezed in between and driven with an extension?

Doozer
04-22-2015, 06:37 PM
In the Solidworks 2015 there is a Hole Wizard option
to make a slotted countersunk hole.
I have never seen a slotted countersunk hole.
Never ever can I recall seeing one.
Wonder if a newbee engineer might design something
with one.
Not totally on topic, just wanted to comment.

--Doozer

plunger
04-22-2015, 06:49 PM
Cant you just tap it and put a stud in there and locktite it. The thickness looks enough ,maybe put four in instead of two

JoeLee
04-22-2015, 07:05 PM
Cant you just tap it and put a stud in there and locktite it. The thickness looks enough ,maybe put four in instead of twoNo, the bracket has to mount against something and there is no access to the other side.

JL.........

iMisspell
04-22-2015, 07:25 PM
Not knowing the application, it does seam like there will be little wall thickness after chamfering.
Take this for what its worth :)
Can you go with alittle wider channel and then use a "spacer" and chamfer the spacer ?

http://i1284.photobucket.com/albums/a570/iMisspell/misc/joelee/channel_zpsfnwjuz61.png


_

JoeLee
04-22-2015, 09:12 PM
The bracket has to slip over something that is why the screw head has to be countersunk, there is no room for any type of filler or button head type screw.

JL................

boslab
04-22-2015, 10:02 PM
Stick a ball end mill in there, it will be a spherical depression as opposed to a conical one but the head of the screw will seat in it, I'm assuming low loading non critical part btw
Mark

Mcostello
04-22-2015, 10:26 PM
Do You have a boring head for a milling machine? The back edge of a boring bar could be ground at 45.

JoeLee
04-23-2015, 07:10 AM
Stick a ball end mill in there, it will be a spherical depression as opposed to a conical one but the head of the screw will seat in it, I'm assuming low loading non critical part btw
MarkI had thought of this. I have some small dremel round burrs and a few dovetail style burrs , not sure of the angle, that might work. The shanks are small enough to fit through the #10 screw hole and I believe the cutting edge goes right to the shank.

JL....................

JoeLee
04-23-2015, 07:11 AM
Do You have a boring head for a milling machine? The back edge of a boring bar could be ground at 45.I do but the boring bar is too big for the hole.

JL.....................

Magicniner
04-23-2015, 05:51 PM
so give me some other ideas?????


(i) Cut a dovetail slot in from the closed side corner slightly shallow to the centre point then lift the cutter lift to give positive location for the screw head.
(ii) Mount it on a lathe face plate and "back bore" the countersink with a hand ground HSS tool.
(iii) Use a dovetail cutter with a shortened and/or reduced shaft, slip it through the drilled hole from the inside & hold with a collet chuck on the outside and use as a reverse countersink

JRouche
04-23-2015, 06:29 PM
Take a small dremel grinding stone, the cylinder shape. While spinning in the dremel motor, grind the shank side of the stone to a nice cone shape. I have a belt sander that works well, a bench grinder would work. Place the shank through the hole and clamp it up to the dremel motor and spin away. Might have to clip the shank of the stone a lil.. JR

JRouche
04-23-2015, 06:50 PM
Like this..... Looking, looking, looking.....



http://i1183.photobucket.com/albums/x461/_GLE_/HSM/Dremel/1_zps8xtznbp1.jpg (http://s1183.photobucket.com/user/_GLE_/media/HSM/Dremel/1_zps8xtznbp1.jpg.html)


AHHH!! There is one.....


http://i1183.photobucket.com/albums/x461/_GLE_/HSM/Dremel/2_zpsyzlz4nnn.jpg (http://s1183.photobucket.com/user/_GLE_/media/HSM/Dremel/2_zpsyzlz4nnn.jpg.html)


Nuther......


Blurry as heck...
http://i1183.photobucket.com/albums/x461/_GLE_/HSM/Dremel/3_zpsrhbiaobu.jpg (http://s1183.photobucket.com/user/_GLE_/media/HSM/Dremel/3_zpsrhbiaobu.jpg.html)

Oh, one more, in diamond too....

http://i1183.photobucket.com/albums/x461/_GLE_/HSM/Dremel/4_zpsm7cpjh2w.jpg (http://s1183.photobucket.com/user/_GLE_/media/HSM/Dremel/4_zpsm7cpjh2w.jpg.html)


Might be some more... Good luck with the project Joe... JR

andywander
04-23-2015, 08:19 PM
A lot of the replies indicate that people think you are wanting to put the screwhead, and the countersink, in the inside corner of the channel.

I think that you want to go straight through the vertical wall of the channel, though the screw in the the photo is pointing sort of at the corner(but I think that's simply because of the shape of the screw, and how it sits there).

The talk of angled washers or triangular pieces makes me think we're not all talking about the same thing.....

EddyCurr
04-23-2015, 08:44 PM
A lot of the replies indicate that people think you are
wanting to put the screwhead, and the countersink, in the inside
corner of the channel.

The talk of angled washers or triangular pieces makes me think
we're not all talking about the same thing.....

Here is part of the OP. At the outset, JoeLee specifically says
he does not want special cutters. The FHSC is shown entering
a hole in the corner of the channel.


I need to come up with a way to countersink a couple holes inside this
piece of cut out rectangular tube for the FHSC screw. Without making some special
cutter or modifying an existing dovetail cutter, I'm at a loss. The inside width is .750.

http://i911.photobucket.com/albums/ac317/JoeLee09/Box%20Bracket/Image003_zpsaopvvjzm.jpg (http://s911.photobucket.com/user/JoeLee09/media/Box%20Bracket/Image003_zpsaopvvjzm.jpg.html)

My suggestion to use a triangular filler or washer would have
pieces where the short sides of the triangle bear against the
side and floor of the inside of the channel and the long side
or hypotenuse provides the face to be countersunk.

However, JoeLee has stated that for his purposes, there can
not be any fillers/washers obstructing the cross section of the
channel.

I am interested to see how the matter is resolved.

.

john hobdeclipe
04-23-2015, 08:45 PM
Try something like these. Just turn the drill bit around or replace it with a length of proper sized rod, then insert into the hole, chuck it in your drill and spin it backwards while pulling.

http://www.homedepot.com/p/Fisch-1-8-in-Steel-Countersink-and-Drill-Bit-Combination-Set-FSH-134800/205205677

http://www.homedepot.com/p/BLU-MOL-9-64-in-Diameter-Drill-Countersink-for-12-Woodscrews-6210/205624243

Woodworking places like Rockler or Woodcraft may have a similar product that would work.

I know it will work...I just tried it a few minutes ago. The trick will be to find one the right size.

EddyCurr
04-23-2015, 08:49 PM
Nice suggestion, john hobdeclipe.

.

RichR
04-23-2015, 10:05 PM
Countersink it on the outside and let the screw pull the metal back in the other direction as you tighten it.

andywander
04-24-2015, 12:42 AM
I don't see a hole there, Eddy. I think you are mistaken. I think the screw is just laying there inside the channel, and the hole has yet to be drilled.

Maybe I'm wrong.....


Here is part of the OP. At the outset, JoeLee specifically says
he does not want special cutters. The FHSC is shown entering
a hole in the corner of the channel.



My suggestion to use a triangular filler or washer would have
pieces where the short sides of the triangle bear against the
side and floor of the inside of the channel and the long side
or hypotenuse provides the face to be countersunk.

However, JoeLee has stated that for his purposes, there can
not be any fillers/washers obstructing the cross section of the
channel.

I am interested to see how the matter is resolved.

.

vpt
04-24-2015, 07:31 AM
Try something like these. Just turn the drill bit around or replace it with a length of proper sized rod, then insert into the hole, chuck it in your drill and spin it backwards while pulling.

http://www.homedepot.com/p/Fisch-1-8-in-Steel-Countersink-and-Drill-Bit-Combination-Set-FSH-134800/205205677

http://www.homedepot.com/p/BLU-MOL-9-64-in-Diameter-Drill-Countersink-for-12-Woodscrews-6210/205624243

Woodworking places like Rockler or Woodcraft may have a similar product that would work.

I know it will work...I just tried it a few minutes ago. The trick will be to find one the right size.



Thats what I was getting at back on the last page. I guess I wasn't clear enough.



Drill the threw hole, insert the countersink bit, grab it from the back side and spin.

EddyCurr
04-24-2015, 10:23 AM
I don't see a hole there, Eddy. I think you are mistaken.Possibly.

But it looks to me like the FHCS is threaded into the corner
of the channel. The tip of a thread tap visible at the right
edge of the photo adds support for the thought there is a
threaded hole present.

.

Paul Alciatore
04-24-2015, 03:48 PM
Another way that should work in aluminum.

Assumption: that looks like a 10-32 screw so I am basing my suggestion on that. If not, then adjust as needed.

1. Make a thick steel washer with a 1/4" hole in it. It should be about 1/4" or more thick.

2. Buy a grade 8, flat head screw, about 3/4" long and a matching nut and washer.

3. Drill your hole in the channel at 1/4" diameter so the 1/4" screw will pass through it.

4. Grease the threads and under side of the head of the 1/4" screw and the grade 8 washer.

5. Place the 1/4", grade 8 screw in the hole, from the inside.

6. Place the thick steel washer on the screw and then the grade 8 washer and nut.

7. Tighten the nut until the grade 8 screw has made a nice countersink depression in the aluminum.

Done.

J Harp
04-24-2015, 10:13 PM
Paul,

I would suggest that some provision be made to run that screw inward to free it from the hole. When I tried something like that, the hole closed in under the screw head, if that happened you wouldn't be able to just push the screw into the channel.

JoeLee,

In the picture is the screw just posing there, or is it threaded into a hole?

Paul Alciatore
04-25-2015, 01:47 AM
Two words,

Bigger hammer!




Paul,

I would suggest that some provision be made to run that screw inward to free it from the hole. When I tried something like that, the hole closed in under the screw head, if that happened you wouldn't be able to just push the screw into the channel.

JoeLee,

In the picture is the screw just posing there, or is it threaded into a hole?

Dan Dubeau
04-25-2015, 10:26 AM
Key hole slot with a dovetail cutter. Make the keys in opposite directions to each other so that the bracket can't fall off if the screws get loose (i.e. either towards, or away from each other).

Another way is to drill a clearance hole through the front for a countersink bit to reach through the slot.

JoeLee
04-25-2015, 03:23 PM
Like this..... Looking, looking, looking.....



http://i1183.photobucket.com/albums/x461/_GLE_/HSM/Dremel/1_zps8xtznbp1.jpg (http://s1183.photobucket.com/user/_GLE_/media/HSM/Dremel/1_zps8xtznbp1.jpg.html)


AHHH!! There is one.....


http://i1183.photobucket.com/albums/x461/_GLE_/HSM/Dremel/2_zpsyzlz4nnn.jpg (http://s1183.photobucket.com/user/_GLE_/media/HSM/Dremel/2_zpsyzlz4nnn.jpg.html)


Nuther......


Blurry as heck...
http://i1183.photobucket.com/albums/x461/_GLE_/HSM/Dremel/3_zpsrhbiaobu.jpg (http://s1183.photobucket.com/user/_GLE_/media/HSM/Dremel/3_zpsrhbiaobu.jpg.html)

Oh, one more, in diamond too....

http://i1183.photobucket.com/albums/x461/_GLE_/HSM/Dremel/4_zpsm7cpjh2w.jpg (http://s1183.photobucket.com/user/_GLE_/media/HSM/Dremel/4_zpsm7cpjh2w.jpg.html)


Might be some more... Good luck with the project Joe... JRWow,, that quite a collection in the box. I don't think that a grinding stone would work well on aluminum.

JL...................

JoeLee
04-25-2015, 03:25 PM
A lot of the replies indicate that people think you are wanting to put the screwhead, and the countersink, in the inside corner of the channel.

I think that you want to go straight through the vertical wall of the channel, though the screw in the the photo is pointing sort of at the corner(but I think that's simply because of the shape of the screw, and how it sits there).

The talk of angled washers or triangular pieces makes me think we're not all talking about the same thing.....Yes, I was kind of getting that impression too. My fault as I should have been a little more descriptive.

JL.................

JoeLee
04-25-2015, 03:27 PM
Here is part of the OP. At the outset, JoeLee specifically says
he does not want special cutters. The FHSC is shown entering
a hole in the corner of the channel.



My suggestion to use a triangular filler or washer would have
pieces where the short sides of the triangle bear against the
side and floor of the inside of the channel and the long side
or hypotenuse provides the face to be countersunk.

However, JoeLee has stated that for his purposes, there can
not be any fillers/washers obstructing the cross section of the
channel.

I am interested to see how the matter is resolved.

.I see where this picture I posted cold be confusing as to the position of the screw but I just set the screw there for the photo not thinking that it may be misleading.

JL.................

JoeLee
04-25-2015, 03:34 PM
OK, anyway.......... I've finished the job. I went with the idea of making a reverse countersink out of one of the screws. I used my dremel with a .030 cut off wheel to slot the screw on four sides. I first had to turn the screw head down to .240 from it;s original .375 to clear the inside wall of the channel. Then I just ground some crude relief angles behind each slot.
I put the screw in the hole and spun it a few times with my drill and done !!! It worked like a charm. I also had to modify the screw heads.
So......... next time anyone has to do some reverse countersinking remember this idea.

JL............


http://i911.photobucket.com/albums/ac317/JoeLee09/Box%20Bracket/Image004_zpsvdmmis0a.jpg (http://s911.photobucket.com/user/JoeLee09/media/Box%20Bracket/Image004_zpsvdmmis0a.jpg.html)
http://i911.photobucket.com/albums/ac317/JoeLee09/Box%20Bracket/Image005_zpspf2py2sm.jpg (http://s911.photobucket.com/user/JoeLee09/media/Box%20Bracket/Image005_zpspf2py2sm.jpg.html)

JoeLee
04-25-2015, 03:37 PM
I can't get a good picture of the relief side of the screw that turned countersink, it's kind of a hack job, but it worked.

JL............

EddyCurr
04-25-2015, 07:36 PM
Good job ! That worked out well.

Even knowing now that the original image shows
a screw lying loosely on its side, it still looks to
me as though the tip is started into an angled
threaded hole. Funny ...

.