Post by tomac on Nov 11, 2003 0:44:53 GMT 10
Regular disclaimer:
I don't take responsibility for injury to yourself resulting from performing the following modifications, nor of any resultant equipment failure. Modification is always outside the intended use of your componentry and you do so at your own risk, with only your own judgement protecting you.
This post is detailed, catering to the newest common denominator.
Drilling.
How to drill, what to drill, why to drill.
First of all, drilling is not for the faint-hearted, the rough rider, and shouldn't be for the beginner. Drilling is a convenient, predictable and accurate way of removing material from componentry, but removing material will always weaken your component.
People will drill all sorts of things that they deem to be overbuilt. The most common things by far are rims, but anything appearing to have deadweight is at the mercy of the weight weeny.
Rims are a popular thing to drill for a few reasons.
1) the material in the centre of the rim is under RELATIVELY less stress than the material at the outside, which supports the sidewalls. Bear in mind however the forces that pulling spokes put on a rim - don't underestimate them.
2) weight at the outside of the wheel, through rotational inertia, slows down acceleration and impedes quick braking. This may be cool for some, but not for me.
3) they are usually made of aluminium, which is pretty soft, and doesn't leave you spending heaps on new drill bits.
I will focus then on drilling rims, anything else you're interested in drilling reply here and we'll talk about it.
anyway how to drill rims - what to think about:
- is your rim really that heavy? will you lose much weight for the inevitable strength loss?
- how wide is your rim? this will determine in part how large your holes can be, as well as being tied to rim strength
- how large can your holes be without:
(a) coming too close to the spoke holes, this could bring on a bout of spoke pullthrough.
(b) coming to close to the sidewall of the rim, there is more force at the outside.
(c) simply losing too much material to hold structurally - particularly important for rear rims and heavy/rough riders
now that you've thought about that you'll need some things:
- 1 drill - for a good, neat, fast job you'll want one that plugs into an outlet and has a cord. It's called a power drill - contrasts with a cordless drill which is relatively gutless for metalwork but will still work OK - might need recharging halfway through - allow time for this.
- 1 set of safety glasses. I use cheap clear ones obtained from a metalshop I used to work in. you can use anything though - sunglasses are perhaps a bit dark for accurate work.
- 1 rim - with no tyre, tube or rim tape. Preferably unlaced from the wheel as well but if you're careful it should be OK.
- a couple of drill bits/hole cutter. You will need your final drill bit (the largest one, will be the size of the holes you are aiming to make in the end) as well as a pilot bit (2-3mm is a good size) for larger holes. You can get away with using a punch instead of a pilot bit for smaller final bits. A hole cutter is different to a drill bit but is still mounted on a drill. Use these for holes over, say, 3/4" in diameter (unless you have a 1" bit lying around, they are expensive). Principles are the same, and get a hole cutter with a built in pilot bit to help you aim straight. I'll just refer to everything generally as "bits".
- rags, a brush and a vacuum cleaner (trust me on this one)
- a lot of time and patience, don't do this the morning of a comp.
You now need to consider how much drilling you will do. Bear in mind that the "inner wall" is in the well of the rim, where the rimtape and tube sits. The "outer wall" is the one you can see when the tyre is mounted, your spoke nipples probably rest in this wall. Will you go through both walls, (assuming you're using a double walled rim, most are nowadays) or just one? if going through both, will you use the same size holes in both? smaller holes in the outside wall will be less prone to letting water and grit in, while smaller holes in the inner wall will be easier (and lighter) to tape up. Most people will go through both walls, using the same size bit. If you are only going through one wall however, go through the inner one. You get a better structure and don't have to worry about dirt and water getting in. Of course if you want cool looks, go the outer wall (I know that's important to everyone :-).
Don't drill the seam, never drill the seam, the seam is already a fragile point, and any drilling will kill it. If you're worried you'll forget to not drill the seam, mark it in some way before you start. The seam of the rim is normally covered by a sticker and is opposite the valve hole. You should be able to see the divide where the rim has been curved from a flat piece of metal and joined at this point.
The first thing to do is to mark the points at which you will drill. This will be dead centred between both the sidewalls of the rim and the two adjacent spoke holes (noting that spoke holes are often offset to each other - therefore not completely centred themselves). You will have to find a way of marking this point perfectly every time, a tiny mistake here will be exaggerated when you start drilling. I used a template piece of sheet metal with a small hole in the centre to stick a pilot bit through and mark the centre - you can also just mark the correct points on a ruler and use that, if you can do it accurately (with a half mm of dead centre for home jobs). As stated earlier, drilling a pilot hole will make it a lot easier to use larger drill bits later (a pilot hole will guide the larger bit at the right point, hopefully preventing it from spinning off course). A punch mark of decent depth will also do the job though, you can make a punch out of any small old screwdriver, just file the end to a sharp point.
you can make punch marks and pilot holes in either the inner or outer walls - but it is perhaps easier to centre them in the outer wall.
now that we've got the holes marked I guess we can start drilling !!
it's a very good and safe idea to put the rim into a vice while you are drilling it. Use rags or timber to stop the metal vice from damaging the soft aluminium rim and don't overtighten it - you just need to stop the rim from vibrating or spinning.
The secret to doing the actual drilling well is - "High speed, low pressure". This means that you should spin the drill bit (hopefully it's sharp, it won't cut straight if it's not) at its fastest speed (excluding bench drills, different kettle of fish) without pressing it too hard onto the job. Just spin it fast and let it work its own way through the material. You will get a cleaner hole this way as the bit won't vibrate all over the place and give you a ragged hole (quiet you :-). Once you've finished drilling, some of the holes may need a bit of cleaning up. Some gentle work with a round file can do this, or you can buy a conical grinding stone to fit into your drill (should be around $1, are often nicely coloured pink) and chamfer the edges of the hole with it for a clean, professional look. You can get a little adventurous here as well. I have drilled out 1/2" holes in both walls (in a sun rhyno lite, could perhaps have gone slightly bigger) and then proceeded to take out another two half inch holes in the INNER wall next to the original hole in each segment. Assuming the same thickness of inner and outer walls this would double my weight saving. See how much material you have left, think of the application, and consider what you can remove. Using grinding tools at this point is sometimes preferable. Further work beyond simple holes should be limited to the inner wall however, not least because it can start to look ugly. Make sure you get rid of all sharp edges which might damage your tube, you should always assume that your rim tape WON'T protect your tube from sharp bits.
Once you've got all the holes drilled and cleaned, try to tap out as many of the shavings as you can (these will be sharp and unpleasant and will get caught between the two walls of the rim) before you break out the vacuum cleaner and use a narrow attachment to try and suck out the rest of the shavings.
Once the rim is drilled, cleaned and freed of all the shavings you can rebuild it (if it isn't already built) but bear in mind that it may build up slightly differently due to a little more give in the rim - allow for this in the break-in period.
Taping the rim will be a different matter now. You will need to use a tape that is wide enough and strong enough to resist the pressure of the tube pushing it out through the holes. Your local hardware store is likely to have a nice selection of electrical and other tape, often in pretty colours. A tip here - put the first layer of tape sticky side up (AWAY from the holes) so that dirt etc doesn't stick to it and discolour it later - this is partly about looking cool after all. Put successive layers of tape down normally so the tube doesn't stick to them and make sure you go right to the edges of the inner wall.
remount your tyre and tube and inflate them very slowly, checking that the rim tape doesn't bulge out so far it will put the tube at risk of damage inside the rim (the tape will bulge out a bit obviously, but you shouldn't be able to see the edges of it coming through the holes).
um yeah - rims drilled all happy (till they fold)
- Joel
I don't take responsibility for injury to yourself resulting from performing the following modifications, nor of any resultant equipment failure. Modification is always outside the intended use of your componentry and you do so at your own risk, with only your own judgement protecting you.
This post is detailed, catering to the newest common denominator.
Drilling.
How to drill, what to drill, why to drill.
First of all, drilling is not for the faint-hearted, the rough rider, and shouldn't be for the beginner. Drilling is a convenient, predictable and accurate way of removing material from componentry, but removing material will always weaken your component.
People will drill all sorts of things that they deem to be overbuilt. The most common things by far are rims, but anything appearing to have deadweight is at the mercy of the weight weeny.
Rims are a popular thing to drill for a few reasons.
1) the material in the centre of the rim is under RELATIVELY less stress than the material at the outside, which supports the sidewalls. Bear in mind however the forces that pulling spokes put on a rim - don't underestimate them.
2) weight at the outside of the wheel, through rotational inertia, slows down acceleration and impedes quick braking. This may be cool for some, but not for me.
3) they are usually made of aluminium, which is pretty soft, and doesn't leave you spending heaps on new drill bits.
I will focus then on drilling rims, anything else you're interested in drilling reply here and we'll talk about it.
anyway how to drill rims - what to think about:
- is your rim really that heavy? will you lose much weight for the inevitable strength loss?
- how wide is your rim? this will determine in part how large your holes can be, as well as being tied to rim strength
- how large can your holes be without:
(a) coming too close to the spoke holes, this could bring on a bout of spoke pullthrough.
(b) coming to close to the sidewall of the rim, there is more force at the outside.
(c) simply losing too much material to hold structurally - particularly important for rear rims and heavy/rough riders
now that you've thought about that you'll need some things:
- 1 drill - for a good, neat, fast job you'll want one that plugs into an outlet and has a cord. It's called a power drill - contrasts with a cordless drill which is relatively gutless for metalwork but will still work OK - might need recharging halfway through - allow time for this.
- 1 set of safety glasses. I use cheap clear ones obtained from a metalshop I used to work in. you can use anything though - sunglasses are perhaps a bit dark for accurate work.
- 1 rim - with no tyre, tube or rim tape. Preferably unlaced from the wheel as well but if you're careful it should be OK.
- a couple of drill bits/hole cutter. You will need your final drill bit (the largest one, will be the size of the holes you are aiming to make in the end) as well as a pilot bit (2-3mm is a good size) for larger holes. You can get away with using a punch instead of a pilot bit for smaller final bits. A hole cutter is different to a drill bit but is still mounted on a drill. Use these for holes over, say, 3/4" in diameter (unless you have a 1" bit lying around, they are expensive). Principles are the same, and get a hole cutter with a built in pilot bit to help you aim straight. I'll just refer to everything generally as "bits".
- rags, a brush and a vacuum cleaner (trust me on this one)
- a lot of time and patience, don't do this the morning of a comp.
You now need to consider how much drilling you will do. Bear in mind that the "inner wall" is in the well of the rim, where the rimtape and tube sits. The "outer wall" is the one you can see when the tyre is mounted, your spoke nipples probably rest in this wall. Will you go through both walls, (assuming you're using a double walled rim, most are nowadays) or just one? if going through both, will you use the same size holes in both? smaller holes in the outside wall will be less prone to letting water and grit in, while smaller holes in the inner wall will be easier (and lighter) to tape up. Most people will go through both walls, using the same size bit. If you are only going through one wall however, go through the inner one. You get a better structure and don't have to worry about dirt and water getting in. Of course if you want cool looks, go the outer wall (I know that's important to everyone :-).
Don't drill the seam, never drill the seam, the seam is already a fragile point, and any drilling will kill it. If you're worried you'll forget to not drill the seam, mark it in some way before you start. The seam of the rim is normally covered by a sticker and is opposite the valve hole. You should be able to see the divide where the rim has been curved from a flat piece of metal and joined at this point.
The first thing to do is to mark the points at which you will drill. This will be dead centred between both the sidewalls of the rim and the two adjacent spoke holes (noting that spoke holes are often offset to each other - therefore not completely centred themselves). You will have to find a way of marking this point perfectly every time, a tiny mistake here will be exaggerated when you start drilling. I used a template piece of sheet metal with a small hole in the centre to stick a pilot bit through and mark the centre - you can also just mark the correct points on a ruler and use that, if you can do it accurately (with a half mm of dead centre for home jobs). As stated earlier, drilling a pilot hole will make it a lot easier to use larger drill bits later (a pilot hole will guide the larger bit at the right point, hopefully preventing it from spinning off course). A punch mark of decent depth will also do the job though, you can make a punch out of any small old screwdriver, just file the end to a sharp point.
you can make punch marks and pilot holes in either the inner or outer walls - but it is perhaps easier to centre them in the outer wall.
now that we've got the holes marked I guess we can start drilling !!
it's a very good and safe idea to put the rim into a vice while you are drilling it. Use rags or timber to stop the metal vice from damaging the soft aluminium rim and don't overtighten it - you just need to stop the rim from vibrating or spinning.
The secret to doing the actual drilling well is - "High speed, low pressure". This means that you should spin the drill bit (hopefully it's sharp, it won't cut straight if it's not) at its fastest speed (excluding bench drills, different kettle of fish) without pressing it too hard onto the job. Just spin it fast and let it work its own way through the material. You will get a cleaner hole this way as the bit won't vibrate all over the place and give you a ragged hole (quiet you :-). Once you've finished drilling, some of the holes may need a bit of cleaning up. Some gentle work with a round file can do this, or you can buy a conical grinding stone to fit into your drill (should be around $1, are often nicely coloured pink) and chamfer the edges of the hole with it for a clean, professional look. You can get a little adventurous here as well. I have drilled out 1/2" holes in both walls (in a sun rhyno lite, could perhaps have gone slightly bigger) and then proceeded to take out another two half inch holes in the INNER wall next to the original hole in each segment. Assuming the same thickness of inner and outer walls this would double my weight saving. See how much material you have left, think of the application, and consider what you can remove. Using grinding tools at this point is sometimes preferable. Further work beyond simple holes should be limited to the inner wall however, not least because it can start to look ugly. Make sure you get rid of all sharp edges which might damage your tube, you should always assume that your rim tape WON'T protect your tube from sharp bits.
Once you've got all the holes drilled and cleaned, try to tap out as many of the shavings as you can (these will be sharp and unpleasant and will get caught between the two walls of the rim) before you break out the vacuum cleaner and use a narrow attachment to try and suck out the rest of the shavings.
Once the rim is drilled, cleaned and freed of all the shavings you can rebuild it (if it isn't already built) but bear in mind that it may build up slightly differently due to a little more give in the rim - allow for this in the break-in period.
Taping the rim will be a different matter now. You will need to use a tape that is wide enough and strong enough to resist the pressure of the tube pushing it out through the holes. Your local hardware store is likely to have a nice selection of electrical and other tape, often in pretty colours. A tip here - put the first layer of tape sticky side up (AWAY from the holes) so that dirt etc doesn't stick to it and discolour it later - this is partly about looking cool after all. Put successive layers of tape down normally so the tube doesn't stick to them and make sure you go right to the edges of the inner wall.
remount your tyre and tube and inflate them very slowly, checking that the rim tape doesn't bulge out so far it will put the tube at risk of damage inside the rim (the tape will bulge out a bit obviously, but you shouldn't be able to see the edges of it coming through the holes).
um yeah - rims drilled all happy (till they fold)
- Joel
