albertz
|
| posted on 26/6/07 at 12:05 PM |
|
|
Hole cutting
I am trying to retro-fit an ST pedal box to my car and have come up against a problem.
Basically i need to cut 2no. 30mm diameter holes through 4-5mm mild steel plate that i have fully welded as my bulkhead at the drivers footwell. I
cannot readily remove the steel plate to a pedestal drill, so am looking for innovative techniques or tools that i can use in situ with basic hand and
power tools.
I have considered using a hole saw, but am not sure how well that will work considering the 5mm thickness.
Maybe the best option is to get the grinder and hack the plate off and drill it properly, it will be a pig of a job and make a bit of a mess
though...
I might be able to get my hands on a magetic based drill which would help, but not too sure if its still available or not.
Any ideas or suggestions gratefully received.
|
|
|
|
|
SeaBass
|
| posted on 26/6/07 at 12:09 PM |
|
|
How about chain drilling it? Centre punch the hole centre. Scribe an arc the size of the hole you want. Choose a smallish drill bit and scribe an arc
which is the diameter hole you want minus 1/2 the diameter of your chosen drill bit. Punch and drill holes all the way round the circumference on the
smaller arc. Tap out the center. File to perfection. Slow but good results.
Cheers
|
|
|
nick205
|
| posted on 26/6/07 at 12:13 PM |
|
|
^^^^^^
Like he said, it's slow, but it does work and doesn't need any special tools
|
|
|
Minicooper
|
| posted on 26/6/07 at 12:20 PM |
|
|
A hole saw will cut 5mm plate fairly easily if a little slow, I have done it several times. Take it slow and keep the drill speed well down, maybe a
little wd40 now and then, don't go fast otherwise you will blunt the holesaw straight away, oh and wear googles
Cheers
David
|
|
|
Davey D
|
| posted on 26/6/07 at 12:22 PM |
|
|
A good quality holesaw would be ok... you would need strong wrists though if it snagged.
when i worked in a fabrication shop we used magnetic pedestal drills. the base has an electromagnet which sticks it to the steel your working on. then
just turn the arm to drill into the surface. they looked like this:
http://www.mytoolstore.com/dewalt/dw159.jpg
as the previous 2 have said. chain drilling is always an option.. just very slow and time consuming
|
|
|
BenB
|
| posted on 26/6/07 at 12:23 PM |
|
|
Go slow. Use a good hole saw. Lots of oil.....
Stitch drilling would work but would leave lots of jaggy edges that would be a right PITA to have to file off manually and you won't get
an angle grinder is such a small hole....
Buying a plasma cutter would be a quick option!! 
|
|
|
davie h
|
| posted on 26/6/07 at 12:33 PM |
|
|
what about drilling a hole big enough to get a die grinder with a metal bit in it and then cut the hole to the correct size i have a cheap one i got
from B&Q and has worked a treat even used in a commercial garage just about every day just need a good air supply
|
|
|
40inches
|
| posted on 26/6/07 at 12:58 PM |
|
|
quote:
Originally posted by CaLviNx
I usually drill the pilot hole first then use a solid bar the same size as the pilot hole as a guide in the hole saw arbor, that way your not gouging
the pilot hole with a drill bit and you avoid making the pilot hole oval or larger thus you get a neat hole as long as you use lots of lubricant
Good idea, plus fix a bolt to the drillbed to stop the work piece spinning
|
|
|
JohnN
|
| posted on 26/6/07 at 05:18 PM |
|
|
Plasma cutter and a wooden template 
|
|
|
David Jenkins
|
| posted on 26/6/07 at 05:34 PM |
|
|
If I was doing such a thing, I'd chain drill as described above, then use an abrasive tip* in my electric drill to smooth off the edges. Slow,
but effective.
David
* 'abrasive tip' - not sure what the proper name is - one of those lumps of abrasive stuck on a steel shaft. As used in die grinders, but
also usable in an electric drill.
|
|
|
Wadders
|
| posted on 26/6/07 at 05:56 PM |
|
|
Iv'e cut through 12mm steel with a 50mm hole cutter, before now with no problems ( other than aching arms). used a mains powered 850-w hand
drill with speed control and a good quality starret hole saw. As said before use a slow speed and some cutting fluid, i use Rocol RTD, it makes a huge
difference. Good tip about replacing the drill with a rod, although it shouldn't wander too much on 5mm plate.
The Rocol stuff also takes the pain out of hacksawing, only downside to it is the smell as it gets hot.
Al.
[Edited on 26/6/07 by Wadders]
|
|
|
SeaBass
|
| posted on 26/6/07 at 07:10 PM |
|
|
quote:
Originally posted by CaLviNx
The chain drilling might work but as said will take forever and is a pain to get a decent finish, avoid at all costs.
[Edited on 26/6/07 by CaLviNx]
I suppose it just depends on how skilled you are Mark. I've used it many times with excellent results. It's all down to the care and
attention you expend when marking out. But then I'm amazed how many kids can't file to a line day in day out.
I certainly wouldn't avoid it at all costs!
|
|
|
albertz
|
| posted on 26/6/07 at 09:39 PM |
|
|
Thanks for all the suggestions.
I actually managed to blag a loan of a mag based rotabroach....job done in about 5 minutes flat. Great machine!
Thanks for all the tips though, handy for future jobs when my blagging skills are not so good!
Cheers
|
|
|
SeaBass
|
| posted on 27/6/07 at 11:08 AM |
|
|
I have a great set of Bosch hole-saws which have seen use on many projects. The best results tend to be when used in a pillar drill with the
appropriate support and security of the workpiece.
I guess I've never been in a rush to complete practical projects as I derive much pleasure from working on things. I like to take my time and
use my head in the process. I can't stand to see a roughly finished rush job.
|
|
|
Hellfire
|
| posted on 27/6/07 at 01:09 PM |
|
|
If you don't own a holesaw it may take less time and money to stitch drill and file. Either way it depends on what tools you have available and
how confident and skillful you are in using those tools.
On the other hand you may have the tools/skills available but achieve greater satisfaction from doing it a different way or perceive the standard of
perfection to be greater.
Phil
|
|
|
