Introduction: Speed Control for Hand Drill Press
Search for "Drill Press" on instructables and you'll find hundreds for making a DIY stand to convert a hand drill into a drill press. What they all lack is a way to control the speed of the drill. If you're using one with a variable speed drill(one in which you control drill speed by the amount of trigger button squeezed), I'll show a cheap, easy and effective method to add drill speed control without opening up the drill or working with complex electronics.
People have added an on-off switch to their drill press handles but when it comes to speed control, they get scared by suggestions of opening up the drill, induction and brushed motors, high voltage and current electronics with transistors, PWM, triacs, etc. These are mostly makers who have made a great drill press stand but haven't much electronics background. So I'll demonstrate how to make one by modifying an el-cheapo chinese hand drill stand with simple bicycle caliper brakes mechanism.
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Step 1: Scrounge or Buy Stuff!
These are the things you will need:
- Hand drill press/stand, preferably a DIY one :)
- Bicycle brake lever.
- Bicycle caliper brake.
- About 1 meter bicycle brake wire with covering. The covering should have preferably have crimped metal caps at both ends. Also, the cable should end in a barrel plug at one end.
- A strip of wood, acrylic, metal or whatever material you like, to provide pivot support for caliper brakes.
- Spare small piece of wood or cork.
- Few tools like hacksaw and drill.
You might have most of these things lying around. You can salvage the brake mechanism from an old useless bike. I got all the materials for less than $4, but that's me being super cheap(as usual). :)
Step 2: Wire Up the Brakes
Take the brake lever and turn it over. One side will have a round hole with a slit till the adjustment screw. Rotate the cable adjustment screw so the cut in it is in line with the slit in the body. Also adjust the nut's cut to be in line. When all 3 are in position, you can easily place the barrel plug at the end of the brake cable in it's holder in the middle of the round hole. Then lay the brake wire through the slit out through the cable adjustment screw's hole, as shown in the second image. Then tighten the nut and screw. Once out of alignment, the wire will not be able to slip out of the slit.
Place the sleeve over the wire. Take the other end of the wire and thread it through the adjustment barrel as shown in the third image. Screw out the adjustment barrel till its maximum. Stretch the wire as much as possible and press the brake pads towards each other slightly. The distance between the pads should be roughly the width of the drill handle including the trigger button. Attach and tighten the loose end of the brake cable to the anchor bolt. Release the pressure from the brakes and they should retain their position. Press the brake lever and the caliper brakes should mimic the movement.
The reason I kept brake lever cable adjustment screw to the tightest and caliper brake adjustment barrel loosest is to aid in adjustments. In Bowden cables, lengthening the housing tightens the cable and shortening the housing loosens the cable. So in this way, if we want less gap between brakes, turn the brake lever adjustment screw out. If you want more gap, turn the caliper brake adjustment barrel in/downwards.
If you face any difficulty in figuring out this step, there are plenty of videos and information on the net on how to wire your bicycle brakes.
Step 3: Attach Brake Lever to Handle
If you have a cylindrical handle, you are saved a bit of pain. Just wrap a roll of electrical tape till the handle body is thick enough to fit the brake lever. Slip on the lever, tighten it and you're done.
If you have a flat handlebar, like mine, then read on. I built 2 semi-cylinders out of wood but then realized I could have just used a piece of cork. Grab a wine bottle, take the cork and slice it in half. Drink the wine and celebrate the fact you saved yourself some useless effort.
If you don't have cork piece or want to make it out of wood, then read on to find how I did it. I first measured out and cut from the wooden strip 2 pieces slightly wider than my handle. Then I marked a semi-circle on them approximately as big as the inside of the brake handle. Then I slices the wood with a hacksaw in a 3D trapezium shape, roughly matching the semi-circles drawn. Using sandpaper, the trapezoid was rubbed into a smooth semi-cylinder. Put some double sided tape to their bottom and stuck them to the handle. Then covered it with a layer of tape(resembles a katana at this point) and slipped on the brake lever. Test it out! I mean test the mechanism, not test slicing stuff with the awesome looking katana. :)
Step 4: Attach Caliper Brake Pivot Bolt Support
Take a strip of any strong material, wood, acrylic, metal, whatever floats yer boat. Measure its intended length and mark the point where the pivot bolt will stick through. Remember, measure twice, cut once. Cut the strip to length and drill an appropriately sized hole at the point you marked.
Find a way to stick this support stick to the body of the drill press. You can drill holes and use nuts and bolts, or some double sided tape(there will hardly be any force on this support), or use superglue. Push the pivot bolt through the hole you just drilled and tighten it using nuts on both sides. Angle the brakes and the drill so that when the jaws of the brakes close, the button gets pressed. The last image shows a close up of how it is to be placed and adjusted.
Step 5: Drill Away!
I wanted to make a DIY drill press stand but due to a lot of other projects and work, I knew I'd never be able to get time to make one. Even if I did, I don't think I'll be able to bring something new to the table, so I went with buying the chinese one but with a few mods of my own.
Contrary to what I feared, it isn't flimsy at all and I have very fine control of the drill speed. I get a very good feedback and I feel as if I'm actually pressing the drill button.
If you leave the brake shoes on, it gives an added benefit of keeping the drill scratch free at points of contact over repeated usage. The brake lever can also be mounted in a different orientation. I chose to put it above my handle but you can rotate it and place it below or on the side. Whatever you feel comfortable with.
Hope this instructable is of use to someone and maybe we'll see new DIY drill stand instructables implementing this mechanism. Thanks for reading!
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