cutting holes in metal for dummies

[mothra]

I've got a mongrel of a z650 with a different swingarm to what I believe it shipped with.

Whats the best way to cut metal... Specifically... I now have three chainguards. None of which the fit properly.

The one that came with the bike fouls on the bottom shock absorbers, so I bought a replacement from the US. Had it powdercoated, then checked if it fit. It didn't. I think most z650s had a plastic guard, I'd like to keep a metal one if possible, so I then bought this one:



As it had a nice big cut out where the shock absorber would go. But the bracket mounts are in completely the wrong place.

So I have the original one that came with the bike that does have the mounts in the right place, and if I cut a hole like the one above it would be ideal. The issue is I’ve already had it powder coated and I want to do a neat job, so I don’t think a hacksaw would be a good answer for me - some of you guys might have more skills. Suggestions would be appreciated, and do you think I’d be able to get away with not having it powder coated again?

Stu

[mick znone]

myself, id angle grind it with a diamond disc, then it would need filing down to take the edges away. put rust inhibitor on the edges immediately, then get some simoniz tough black paint on it.

[Steve Cooke]

It wont be too easy to protect the finish but if I were to try it I think I would series drill it with a small drill bit it then Dremel it smooth slowly so as not to build up too much heat and then touch in the bare edge.

[Dark Skies]

If the hole doesn't have to have square angles why not use an appropriately sized HSS hole saw?



You make two holes that met up in the middle to create an oval shape for a closer cut to the shock rather than one big hole. Use strong adhesive tape like duct tape to stop the pilot hole skittering on the initial cut and to help prevent chrome from lifting.

[Rich]

Powder coating is relatively inexpensive, cutting a hole in something is intrusive, put it down to experience. Taking it slowly and not allowing the heat to build up will make your existing finish look better but it is still going to have a big hole in it! You could edge it with rubber trim, but by the time you've finished sourcing it it may be just as expensive as having it redone.

Grind the part away with a grinder, making sure that it was covered against flying sparks, take it slowly to stop the heat build up.

Alternatively I would make one out of 16g alloy sheet.

[mothra]

Thanks for the advice gents. I sort of squished it all together, and attacked it with a dremel. I was a bit worried about it cos if I messed it up, I had no idea what the mudguard that fits is actually from, and probably couldn't replace it....

So it was pretty succsessful - neat cuts that I cleaned up afterwards, then stopped trying to take shortcuts and sent it off to be repowdercoated...