100% Biker & Trike Magazine Forums

Go Back   100% Biker & Trike Magazine Forums > 100% Biker > The Workshop

Notices

Reply
 
Thread Tools Display Modes
  #1  
Old 14-08-2004, 06:37 PM
Mitch's Avatar
Mitch Mitch is offline
Talk, Type, Breath, Talk, Type, Breath....
 
Join Date: Apr 2004
Location: Between the Sea and the South Downs
Posts: 4,802
Default Angle Grinder, let me introduce you to frame tubes... help!!

I need some advice... dum dum dah!!!!

I want to cut about eight inches of rear subframe off my GT750 to make way for the new mudguard & solo seat and I'm not sure whether I should use a hacksaw, or go out and get an angle grinder.

The problem is with an angle grinder, I've never used one me sen (only watched other people) and I'm not sure how to use one Also, I've heard they can be quite lethal if you allow yourself to get distracted - for example, Cookie (Kent HA and that Monster Garage thing off't telly) almost lopping his thumb off with one.

What do you suggest?

Also, what do I do wi't big holes at the end when I've cut the tubes? I know Mrs R's bike has already had this done (by someone who knows what he's doing by the looks of things) Should I use some sort of filler or something?
__________________
Grav says: "...It never fuckin' ends......... "

Switch off TV, get a life... www.whitedot.org
Reply With Quote
  #2  
Old 14-08-2004, 06:48 PM
smeghead's Avatar
smeghead smeghead is offline
Billy No Mates (only virtual ones!)
 
Join Date: Jun 2004
Posts: 1,128
Default

use both the grinder will make short work of the tube, but the hacksaw will make a neater cut(in inexperianced hands) as for the hole left cut a piece of plate and weld it in, and clean it up with a grinder, blackjack uses these wierd discs ,witch give amazing results hth
Reply With Quote
  #3  
Old 15-08-2004, 12:30 AM
Alik Windrush Alik Windrush is offline
Chatter Box
 
Join Date: May 2004
Location: Essex
Posts: 275
Default

Try a steel stockist or trailer place and you should find that you can get nice plastic bungs which you can hammer into the end of you tube if you're not up for welding.
Try not to cut any structural bits out of your frame such as bracing tubes for the rear suspension top mounts.
Reply With Quote
  #4  
Old 15-08-2004, 01:40 AM
dracken1's Avatar
dracken1 dracken1 is offline
Talk, Type, Breath, Talk, Type, Breath....
 
Join Date: Apr 2004
Location: west mid wales
Posts: 4,493
Default

quite often you will find the frame is under stress.
this shows itself up as the tubes you are cutting closing up on the hacksaw/ grinder.

to get used to using a grinder cut some solid rod before attemting tube.
when you get the hang of it try using it plugged in
Reply With Quote
  #5  
Old 15-08-2004, 02:49 PM
Blackjack Blackjack is offline
Been out, but rather stay in!
 
Join Date: May 2004
Location: Bristol
Posts: 1,301
Default

Important point.

You don't cut metal with a grinding disc, you use a cutting disc.

A grinding disc is about 1/4" thick, cutting discs are about 1/8" thick.

If you go to Machine Mart or somewhere and buy a grinder it will almost inevitably come with a grinding disc. So get a few cutting discs that suit the grinder. Angle grinders come in several sizes, but what you want is a 100mm (4") or a 115mm (4 1/2") preferably the 115mm. The discs for them have different sized fixing holes so make sure you get the right one. When you change the disc, look at the "nut" that retains it and you'll see it has a shoulder on it. When you use a grinding disc the shoulder goes into the hole in the disc, but for a cutting disc the nut get's flipped over as the shoulder will prevent it from gripping the thinner cutting disc.

Goggles or a headshield are an obvious must, but be careful about what you wear, as the spray of sparks can set you're clothing on fire not to mention getting loose clothing caught on the wheel and dragging parts of your anatomy into contact with the wheel. Gloves are a bit of a contraversial thing as they can prevent you from inflicting fairly minor injuries on yourself, but they can also get dragged into the wheel and cause some pretty nasty injuries.

Using a cutting disc you should "saw" back and forth with the wheel not just press it into the material. Try and work your way around the cut rather than cutting it all from one side as when there is a lot of disc in the cut there is the danger of it grabbing and ripping the grinder out of your hand. Which is fun.

You want to be cutting from the top down so that as the bit you're cutting off starts to sag the cut opens up, rather than closing up as it would if you cut from the bottom up.

The "weird" discs Animal referred to are fibre backed flexible discs that get used with a nylon backing disc and a different nut. They come in different grits (24, 60, 80, 120 in descending order of roughness) and are best used for metal finishing, flushing off non structural welds, and so on.

As for the end ot the tube you'll probably find you end up cutting off some of the gusset that runs backwards from the top shack mount this gives you a round hole and a squarish one underneath it. Tends to make the plastic bung a bit unworkable. So I'd be cutting out a metal blanking plate and welding it on. If you decide to fill it use something like P40 or any fibre glass bridging filler as normal body filler is porous and holds water which causes corrosion problems and lifts any paint plus bridging filler will "bridge" holes without sagging anything like body filler does. You can finish off the bridging filler with body filler (bridging filler doesn't "shape" very well).
Reply With Quote
  #6  
Old 16-08-2004, 05:18 PM
Mitch's Avatar
Mitch Mitch is offline
Talk, Type, Breath, Talk, Type, Breath....
 
Join Date: Apr 2004
Location: Between the Sea and the South Downs
Posts: 4,802
Default First cut is the deepest!!

Just cut one side of the frame!!!! Having a cup of coffee and a lie down before I do t'other side to recover!!!!! (sort of thing Mrs R would do in a victorian feint stylee!)

Thanks for your advice guys, will go out and get a grinder to do the fiddly bits. For now the hacksaw will suffice!
__________________
Grav says: "...It never fuckin' ends......... "

Switch off TV, get a life... www.whitedot.org
Reply With Quote
  #7  
Old 16-08-2004, 06:23 PM
Mitch's Avatar
Mitch Mitch is offline
Talk, Type, Breath, Talk, Type, Breath....
 
Join Date: Apr 2004
Location: Between the Sea and the South Downs
Posts: 4,802
Default ... and the second cut's much more fun!

Done it!!!!!

It's one of those things where you get the confidence to do something for the first time, by yourself with no-one lookin' over your shoulder. tomorrow, I'll be out there with the filler...

Up until this bike, I've let everyone else do everything but now, I've started to take things apart (and put them back together) - like forks, I'd never even taken a set of forks off before now and I've been riding bikes for 14 years I'm even teaching Mrs R's Sprog how to do stuff to his bike...

OK so I can't weld and my painting's not brilliant, though not that bad for someone who hasn't painted bikes since my CX back in 1992! at least there are no grey or red bits, where the primer or the old colour shows through but I'll get there eventually.

Sun's come out from't clouds, Mrs R's home from work in less than an hour and we're off t'pub for a nice bevvy! *basks in the glory for a bit*
__________________
Grav says: "...It never fuckin' ends......... "

Switch off TV, get a life... www.whitedot.org

Last edited by Mitch; 16-08-2004 at 06:26 PM.
Reply With Quote
  #8  
Old 20-10-2004, 01:36 PM
Sankey Sankey is offline
Chat Virgin
 
Join Date: Oct 2004
Posts: 42
Unhappy angle grinder

just use gas axe its much more fun, and you can then chase the bits of tube you've cut off around the garage floor with said angle grinder and watch as it destroys everything in its path, just holding it by the lead is best as there is less control.

DONT DO IT IAM ONLY JOKING FOLLOW SOMEONE ELSES ADVISE AS I AM NOT FEELING MYSELF AS LATE.
__________________
gas axe (makes just as much mess but its more fun)
Reply With Quote
  #9  
Old 20-10-2004, 05:34 PM
Mitch's Avatar
Mitch Mitch is offline
Talk, Type, Breath, Talk, Type, Breath....
 
Join Date: Apr 2004
Location: Between the Sea and the South Downs
Posts: 4,802
Default

Quote:
Originally Posted by Sankey
just use gas axe its much more fun, and you can then chase the bits of tube you've cut off around the garage floor with said angle grinder and watch as it destroys everything in its path, just holding it by the lead is best as there is less control.

DONT DO IT IAM ONLY JOKING FOLLOW SOMEONE ELSES ADVISE AS I AM NOT FEELING MYSELF AS LATE.
Yeah...um...right you are there sor! Feck, put this thread on back in August... I thought it had gone to the place where threads went to die!

Have not yet bought an angle grinder, but have used Topper's to great effect (angle grinder that is you nerks!!) on the mudguard and whatnot - as well as cleaning up the frame - so very happy
__________________
Grav says: "...It never fuckin' ends......... "

Switch off TV, get a life... www.whitedot.org
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 06:09 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.