Cycling UK Forum

does any one know of a cheap (hand) drill that will take an 8mm drill bit. I need this to drill out my rims to take a Schrader valve should I decide to go down that route. The one I have stops at 6mm and one I bought off Ebay also 6mm ( though advertised as 10mm) I dont want to buy an expensive drill that I will probably only ever use this once.

you need quite a lot of torque to get an 8mm drill through a rim. Most hand drills won't manage that amount of torque.

I think you are doing exactly the wrong thing by wanting to convert to Schrader valves BTW.

cheers

If you are still determined to give it a try, after Bruce's comments, you can buy an 8mm bit with a 1/4" hex shank, which should fit your existing chucks.

Here is a hole cutter which would do it: https://www.ebay.co.uk/itm/6-25mm-Step-Drill-Bit-HSS-Titanium-Coated-1-4-Hex-Shank-Wood-Metal-Cutter-BI447/163041853411?hash=item25f60d3fe3:g:aXsAAOSwAjRa9KTv

Or a more expensivebdrill bit: https://www.ebay.co.uk/itm/Alpen-8-0mm-x-120mm-Profi-Multicut-Multi-Purpose-Drill-Bit-with-1-4-Hex-Shank/231814175474?epid=1757903021&hash=item35f9339af2:g:x2QAAOSwCypWmCZu

Both are likely to be difficult to use in a hand drill.

Brucey wrote:you need quite a lot of torque to get an 8mm drill through a rim. Most hand drills won't manage that amount of torque.

I think you are doing exactly the wrong thing by wanting to convert to Schrader valves BTW.

cheers

well I have already tried it on an old rim that is junk. was able to get the 8mm bit into my hand drill just wouldnt tighten well, so was skew. But was able to get thru reasonably cleanly, producing a spiral shaving, quitr easy considering the bit was a bit skew, I must have strong hands -it only has to make the hole larger rather than drill a hole from scratch. my hand drill with only take up to 6mm.

well I like schrader valves, never had any problems with them and less faff than inserting a converter then the pump. Any way just want the option at the moment
my old hand drill is an ancient Stanley one maybe 50+ years old belonged to my my dad and maybe his before that.

thanks Airsporter1st for the info about smaller shank 8mm bits. I'll see what is available hopefully cheaper

That cone bit is rather strange. Any one ever use one?

mercalia wrote:

Brucey wrote:you need quite a lot of torque to get an 8mm drill through a rim. Most hand drills won't manage that amount of torque.

I think you are doing exactly the wrong thing by wanting to convert to Schrader valves BTW.

cheers

well I have already tried it on an old rim that is junk. was able to get the 8mm bit into my hand drill just wouldnt tighten well, so was skew. But was able to get thru reasonably cleanly, producing a spiral shaving, quitr easy considering the bit was a bit skew, I must have strong hands -it only has to make the hole larger rather than drill a hole from scratch. my hand drill with only take up to 6mm.

well I like schrader valves, never had any problems with them and less faff than inserting a converter then the pump. Any way just want the option at the moment
my old hand drill is an ancient Stanley one maybe 50+ years old belonged to my my dad and maybe his before that.

thanks Airsporter1st for the info about smaller shank 8mm bits. I'll see what is available hopefully cheaper

That cone bit is rather strange. Any one ever use one?

They are mainly for sheet metal. I've used them on e.g. junction boxes on the industrial side. If your rim is double walled, you'd obviously need to use it from both sides, because you only insert it as deep as needed for the required hole diameter.

A rat tailed file might do the job pretty quickly and not leave any sharp edges if you dont know anyone with a drill.

Stewart H wrote:A rat tailed file might do the job pretty quickly and not leave any sharp edges if you dont know anyone with a drill.

well I just did a google and finding a rat tailed file that will do 8mm is hard espcially as sellers dont want to tell the max diameter just say the length as if that is important

Hi
Local engineering co turned smaller shanks onto large diameter drill bits for me; do you know someone with a lathe?
Regards
tim-b

mercalia wrote:

Brucey wrote:you need quite a lot of torque to get an 8mm drill through a rim. Most hand drills won't manage that amount of torque.

I think you are doing exactly the wrong thing by wanting to convert to Schrader valves BTW.

cheers

well I have already tried it on an old rim that is junk. was able to get the 8mm bit into my hand drill just wouldnt tighten well, so was skew. But was able to get thru reasonably cleanly, producing a spiral shaving, quitr easy considering the bit was a bit skew, I must have strong hands -it only has to make the hole larger rather than drill a hole from scratch. my hand drill with only take up to 6mm.

well I like schrader valves, never had any problems with them and less faff than inserting a converter then the pump. Any way just want the option at the moment
my old hand drill is an ancient Stanley one maybe 50+ years old belonged to my my dad and maybe his before that.

thanks Airsporter1st for the info about smaller shank 8mm bits. I'll see what is available hopefully cheaper

That cone bit is rather strange. Any one ever use one?

you mean a step drill? they work fine.

why not pop down the lbs - can't see them charging you much for doing it.

you must know someone with a regular drill.

mercalia wrote:

Stewart H wrote:A rat tailed file might do the job pretty quickly and not leave any sharp edges if you dont know anyone with a drill.

well I just did a google and finding a rat tailed file that will do 8mm is hard espcially as sellers dont want to tell the max diameter just say the length as if that is important

Chainsaw sharpening files always state the diameter.

a standard HSS drill bit is soft on the shank; this means that three flats can be filed on it and it can be made to tighten properly in some drills with small chucks.

cheers

Stepped drill bits are great for thin/sheet materials. Normal bits have a tendency to take a big bite and start self feeding like a screw in thin materials. This results in a ragged, non circular hole. Even if they don't do this you often get a triangular hole if you are just enlarging an existing one slightly.

I'm not sure that these are issues for drilling rims specifically but I've always used the stepped bits with good results.

Brucey wrote:a standard HSS drill bit is soft on the shank; this means that three flats can be filed on it and it can be made to tighten properly in some drills with small chucks.

cheers

thanks for that I just been trying that and seems to work fine, saved me some cash thanks. I bought some metal HSS drill bits from Lidl the other week just £4 for a set. lucky I have a file apart from sockets and spanners and hex keys that and the ancient drill thats all I have

glad it worked OK for you

cheers