Solcar
10 kW
Making a new input shaft for my gearbox, I have to drill perpendicular holes for pins to lock the gears or cogs in place. Anyone have a trick or two to get good holes reliably?
Drilling rod with a straight hole by hand
- Thread starter Solcar
- Start date
Gordo
100 kW
Solcar said:
Not 100% sure of what you are doing or what you mean "by hand?" If you are using a motorized hand held drill, DON'T, make or get a cheap press to mount your hand drill motor in; http://www.instructables.com/id/Portable-tool-work-bench/step2/Hand-drill-press/
OR for $60 http://www.harborfreight.com/5-speed-drill-press-38119.html
To drill your shafts;
Get a steel cube, 1" to 1 1/2" and drill a hole though the center of the cube, the size of your shaft. Drill a hole perpendicular through the first hole, the size of your pin. Put your shaft in the hole and drill through the shaft. Perfect every time.
I have never bought a tool, no matter how expensive, that did not pay for itself many times over during the time I have owned it. This includes a $3000 MIG welder purchased @ 1980, when I did not even know how to weld AL.
Solcar
10 kW
Thanks for describing that methodology, Gordo. I must be really untalented as a machinist because my holes never are close enough in the block jig approach. That is, my bock type jig had holes that were off by too much.
I wish I were a machinist by trade in this regard, then I would be able to justify having more than simple hand tools. Since my specialty is analog electronics my shop is already full of things needed for that. My bro-in-law gave me a drill press, but it was too sloppy and loose to work at all.
Yet, an ebike has both mechanical and electrical components. So, I haven't a reasonable alternative other than bearing with getting the mechanical part done as best as I can.
So far, the best results have been from making a jig out of rebar tie wire. I wrapped the wire around the drill bit in a tight spiral. It is easier to do most of the wrapping around the shank of the drill bit where it is smooth. Be careful not to bend and snap the bit. I clamp the beginning end of the wire to the drill bit shank with visegrips and then make the tight spiral. Keep unclamping and reclamping the visegrips closer to the end of the coil as you grow the spiral, in order to prevent the bit from bending and breaking.
Then, leaving the drill bit within the coils, place it against the rod perpendicularly. Take the closest free end of the wire (actually in contact with the rod already) and wrap it around the rod a few times. then take the farthest free end and bend it sharply down toward the rod, and then wrap it around a few times as well.
Now comes the tricky part. Adjust the spiral (coil) so that it is perpendicular to the rod along both axes. The axis along the length of the rod is the easy one. It is the one that aligns with the curved surface that is the hard one to get right. Getting that one wrong causes the hole to be drilled subtending an arc on the cross section rather that passing through the diameter. Getting it crooked prevents the pin from aligning with the holes in the sprocket or gear to be pinned.
This way is a bit of trouble, but it still gives much better results than drilling free-hand. When drilling, hold the rod by means of the visegrips that are clamping the jig in place, at the jaws end rather than the handle end, though. Prior to drilling, look through the coils of the jig and center the pilot hole, that is needed in the rod to insure a sure start of the hole. The visegrips are locked when the pilot is visibly centered at the rod-end of the coil when sighting through its inside.
I have been using a drywall screw to dig into the rod to make a beginning pilot indenture. If a drywall screw is locked in a pair of visegrips, it is easy to dig it into the soft steel with quite some force. I find it easier than using a hammer and punch. Caution: beware of the screw slipping and puncturing fingers or hand. Once the screw has made a small indenture, use the drill bit and drill to drill into the metal about a millimeter or two. That hole is what is centered at the bottom of the coil. When drilling the hole through the rod using the jig, it is important not to force it too much, or it will deflect and drift off the mark. I find this generally true when drilling metal for other things, too.
I noticed that my cobalt bit was no longer doing much penetrating. I decided to use my dremel with the diamond-impregnated cutting wheel to sharpen it up. After that, it seemed to go through faster that it did when the bit was new. Basically, grind off 100 microns (.1mm) of the tip to sharpen ti so that the end spe is the same as the original, but just a tiny bit shorter.
I wish I were a machinist by trade in this regard, then I would be able to justify having more than simple hand tools. Since my specialty is analog electronics my shop is already full of things needed for that. My bro-in-law gave me a drill press, but it was too sloppy and loose to work at all.
Yet, an ebike has both mechanical and electrical components. So, I haven't a reasonable alternative other than bearing with getting the mechanical part done as best as I can.
So far, the best results have been from making a jig out of rebar tie wire. I wrapped the wire around the drill bit in a tight spiral. It is easier to do most of the wrapping around the shank of the drill bit where it is smooth. Be careful not to bend and snap the bit. I clamp the beginning end of the wire to the drill bit shank with visegrips and then make the tight spiral. Keep unclamping and reclamping the visegrips closer to the end of the coil as you grow the spiral, in order to prevent the bit from bending and breaking.
Then, leaving the drill bit within the coils, place it against the rod perpendicularly. Take the closest free end of the wire (actually in contact with the rod already) and wrap it around the rod a few times. then take the farthest free end and bend it sharply down toward the rod, and then wrap it around a few times as well.
Now comes the tricky part. Adjust the spiral (coil) so that it is perpendicular to the rod along both axes. The axis along the length of the rod is the easy one. It is the one that aligns with the curved surface that is the hard one to get right. Getting that one wrong causes the hole to be drilled subtending an arc on the cross section rather that passing through the diameter. Getting it crooked prevents the pin from aligning with the holes in the sprocket or gear to be pinned.
This way is a bit of trouble, but it still gives much better results than drilling free-hand. When drilling, hold the rod by means of the visegrips that are clamping the jig in place, at the jaws end rather than the handle end, though. Prior to drilling, look through the coils of the jig and center the pilot hole, that is needed in the rod to insure a sure start of the hole. The visegrips are locked when the pilot is visibly centered at the rod-end of the coil when sighting through its inside.
I have been using a drywall screw to dig into the rod to make a beginning pilot indenture. If a drywall screw is locked in a pair of visegrips, it is easy to dig it into the soft steel with quite some force. I find it easier than using a hammer and punch. Caution: beware of the screw slipping and puncturing fingers or hand. Once the screw has made a small indenture, use the drill bit and drill to drill into the metal about a millimeter or two. That hole is what is centered at the bottom of the coil. When drilling the hole through the rod using the jig, it is important not to force it too much, or it will deflect and drift off the mark. I find this generally true when drilling metal for other things, too.
I noticed that my cobalt bit was no longer doing much penetrating. I decided to use my dremel with the diamond-impregnated cutting wheel to sharpen it up. After that, it seemed to go through faster that it did when the bit was new. Basically, grind off 100 microns (.1mm) of the tip to sharpen ti so that the end spe is the same as the original, but just a tiny bit shorter.
StudEbiker
100 kW
The drywall screw technique can easily be done with one of these: http://www.harborfreight.com/spring-loaded-center-punch-621.html
Very useful for the operation you described. If you are talking about dimpling a shaft for set screws, I was able to successfully do that free hand using a hand drill and the center punch.
I just put the rod I was drilling in between the boards on the deck so it wouldn't roll and it wasn't tough. I did have some other issues unrelated to drilling the set screws though.
Very useful for the operation you described. If you are talking about dimpling a shaft for set screws, I was able to successfully do that free hand using a hand drill and the center punch.
I just put the rod I was drilling in between the boards on the deck so it wouldn't roll and it wasn't tough. I did have some other issues unrelated to drilling the set screws though.
Solcar
10 kW
Thanks, indeed, those dimples are like pilot holes, and I have some set screw-type sprockets that I may try securing like that, free-hand drilling the shallow holes.
That springloaded punch seems really effective. My guess is that the user cocks it then can get really close eyes on the work piece to get it right on the mark, and the press a release. Now that should get it close. Safety glasses highly recommended.
P.S. I'm to the point of wearing two pairs of reading glasses at the same time for close work. That relieves eyestrain and magnefies about ten times, hands-free.
That springloaded punch seems really effective. My guess is that the user cocks it then can get really close eyes on the work piece to get it right on the mark, and the press a release. Now that should get it close. Safety glasses highly recommended.
P.S. I'm to the point of wearing two pairs of reading glasses at the same time for close work. That relieves eyestrain and magnefies about ten times, hands-free.
mat h physics
100 W
I have trained as a machinist/tool maker and here is the way it should be done. Using a vise, mount the rod horizontal. Get a CENTER DRILL, usually from an industrial supply house. Hardware stores will not carry them, body shops call them spot drills used for removing rivets. They are designed to prevent "walking", center punching a start spot helps as well. Ramp the spindle as fast as possible, as slower speed will break the tip. Even a hand drill will be too slow.
Standard bits flex way too much, and risk snapping. Here is an example, get the smallest http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=260848507613+
Once a pilot hole is est, use a conventional bit, and a vise and drill press are NEEDED for this.
Use cutting oil, or even 3n1. Lube is important for steel on steel.
Standard bits flex way too much, and risk snapping. Here is an example, get the smallest http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=260848507613+
Once a pilot hole is est, use a conventional bit, and a vise and drill press are NEEDED for this.
Use cutting oil, or even 3n1. Lube is important for steel on steel.
Solcar
10 kW
That means it can't really be done by hand. But we non-professional folks without a fabricating shop have to do these things. 
Thanks for describing the way the pros do it. I was almost going to ask someone here to make changes to a gearbox for me. But doing it oneself is such an effective means to gaining understanding on how things really and truly tick. I realized that by the time I got it all explained and set up with someone, I could have made a functional version. In fact, it can be hard to see what is needed before actually trying to do it.
That picture of the center drills could have been taken by me on my camera. That still look familiar, like i've seen some 0f those somewhere before.
I really liked the machinist who worked at the electronics factory I was employed at.
Thanks for describing the way the pros do it. I was almost going to ask someone here to make changes to a gearbox for me. But doing it oneself is such an effective means to gaining understanding on how things really and truly tick. I realized that by the time I got it all explained and set up with someone, I could have made a functional version. In fact, it can be hard to see what is needed before actually trying to do it.
That picture of the center drills could have been taken by me on my camera.
That still look familiar, like i've seen some 0f those somewhere before.I really liked the machinist who worked at the electronics factory I was employed at.
StudEbiker
100 kW
Solcar said:
The pin is spring loaded, but you just press the tip right on the spot you want to make your hole and the spring compresses until it reaches a certain point and it releases itself putting a nice mark on the metal. SO you don't have to "aim" it and release, you just put it on the spot and press. The punch does the rest for you.
Solcar
10 kW
That's clever.
Gordo
100 kW
Solcar said:
mat h physics
100 W
If this is a single hole, I'd suggest seeing if the local machine shop will punch it for $10. Having had a $40 drill press from HF for a while I take it for granite. Bought small center dill to drill holes at an angle.
Small drills bits require high speeds, so they won't break. A lager center drill bit may work on a hand drill, but you are looking a small carter key hole. Expect to break drill bits smaller than 1/8" in a hand drill.
PS DO NOT USE diamond/carbide, on steel. Once high temps are achieved, the carbon will literally absorb into the steel (chemically).
Small drills bits require high speeds, so they won't break. A lager center drill bit may work on a hand drill, but you are looking a small carter key hole. Expect to break drill bits smaller than 1/8" in a hand drill.
PS DO NOT USE diamond/carbide, on steel. Once high temps are achieved, the carbon will literally absorb into the steel (chemically).
Solcar
10 kW
I remember, now, it is a strange drill press. I'm not surprised at its poor performance since it used large hose clamps to attach a hand drill's body to a metal slab that moved up and down via a toothed sled. The handle has a gear at its pivot, and that meshes with the cogged track. 
Bearings on a hand drill most certainly would have too much play for it to drill a good hole.
----
Using a jig removes bearing play from the situation. Then a hand drill can make a decent hole, with care.
Bearings on a hand drill most certainly would have too much play for it to drill a good hole.
----
Using a jig removes bearing play from the situation. Then a hand drill can make a decent hole, with care.
Solcar
10 kW
mat h physics said:
I got the first hole done and next time I can get into the shop, I can see if it is really satisfactory. The dull bit actually saved it from failure, because when I noticed that I had forgotten to adjust the side-to-side axis, the bit had stopped making any further progress at drilling the hole. So, once I noticed that, I measured out the exact opposite-side point of where the hole was supposed to exit, and I started a new hole from the back side to meet the original hole that was off. The intersection, and resulting hole all the way through appear to be good.
There is a metal fabrication factory in the neighborhood. I was recently wondering about them. It would be nice to check them out if I get an adventurous feel sometime. I think they would be pretty unaffordable in general, however.
On using diamond on steel, I know what you mean. Once I decided to salvage a bunch of old bike frames by cutting them with the diamond blade on my circular saw. Thinking was, of course, hardest substance cutting metal--ought to be a breeze. And it was, except that I just noticed in the nick of time that my $50 blade was rapidly eroding. Though it is for cutting concrete and masonry, it probably would have worked if it could have cut very slowly to keep the temperature down, or maybe with water-cooling of the cut.
There didn't seem to be a problem using the diamond wheel on the dremel to sharpen the drill bit. It was set on the slowest setting. That fits what I remember reading somewhere--keep the speed down when using diamond to abrade steel.
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