Getting a perfectly square cut

[breezer]

Hi all,

I'm in the process of fabricating a different kind of scooter engine stand to those I normally make. Part of the job requires a very square cut on a piece of 50mm x 25mm box - about 250mm long - as it will be stood on it's end.

If it was a smaller size, or better shape I'd stick it in the lathe and face it off, and I don't have access to a milling machine.

I'll be cutting it with an evolution rage saw, which will give a good cut, good enough for welding together, but not a perfect cut.

I also have a linisher, which is great for tidying up ends, but again a perfect cut end would be achieved more by luck than planning as the angle table tends to flex.

Any other ideas?

Is there a way of doing this with a tool mounted in the lathe chuck and solid mounting the workpiece on the cross slide?

Cheers

Jim

 

[CRB]

Is there a way of doing this with a tool mounted in the lathe chuck and solid mounting the workpiece on the cross slide?

Clamping to the lathe cross slide is probably the quickest way, since you have access to one. You only need to clock the length and the rest is done for you.

Though if you are likely to need more of the same spend some time adjusting the saw to cut true. You could do them on the lathe with a stop or two, but the saw would be quicker.In fact do the saw anyway, so it is right.

 

[breezer]

What would be the best tool to stick in the lathe - some sort of milling cutter (I have a couple)

I think the problem with the saw is flex in the blade, especially when you're asking it to cut through biggish chunks of metal - like I say - if the cuts are being welded together it's not an issue as I can set everything up, and the difference is pretty negligable, and works like a root gap.

 

[mike os]

not easier too get someone to do it for you.....?

 

[hotrodder]

Which way do you cut square/rectangular tube? Like [] or like <>? The later (while obviously no good with mitres) makes for a better cut. I can't remember what's what with Evolution rage saws but assuming it's a 'chopsaw' style rather than laid out like a compound mitre wood saw you just need to make a simple fixture that bolts to the fence so the work can be clamped securely. Granted my Dewalt is a different animal but with care it can make perfectly square cuts

While clamping/bolting the stock to the cross slide of a lathe will let you feed it in two directions you won't have a Z axis i.e. you'd need a cutter larger than 25mm dia and a very light touch if you don't want to break the tool.

For one piece i'd use a file and a square to true up the cut
For multiple pieces/because it'd be useful/clinically unable to file something without making it more wonky i'd rework the linisher so the table is useful

 

[breezer]

Where's the fun in that Mike?

 

[mike os]

sorry? this is meant to be fun?

i thought it was for work...

in that case a file & square

 

[gordon stephenson]

If not too many pieces I'm with Hotrodder, accurately scribe lines,chop saw and check and finish with a decent file

 

[breezer]

Cheers HR. Yeah I cut like [] & the rage saw is like a compound mitre saw but designed to cut steel too.

I have a few of these to do and always keen to learn new techniques which I can use in future on other jobs.

I'll look at a better clamp to the fence and also look at beefing up the table on the linisher - hopefully the two will give me what I need.

If all that fails I'll look for someone with a mill!

Mike - anything is fun compared to work... ;-)

 

[mike os]

i hear that one ;-)

 

[FranV8]

If you're going to use the lathe as a mill, how about a slitting saw in a suitable arbor, your lathe probably has a Morse taper in the spindle so it could be mounted with a draw bar perhaps? Or a plain shank arbor held in the chuck?

 

[Buzza]

What would be the best tool to stick in the lathe - some sort of milling cutter (I have a couple)

Use a fly cutter, something like these : http://www.rdgtools.co.uk/acatalog/FLY_CUTTERS.html

 

[eil]

A slitting saw made with a rage blade perhaps like http://madmodder.net/index.php/topic,7563.0.html

 

[breezer]

I was wondering whether a fly cutter might work...

A slitting saw made with a rage blade perhaps like http://madmodder.net/index.php/topic,7563.0.html

 

[CRB]

Fly cutter, large diameter face mill or a lathe facing bit in a four jaw chuck.

 

[greek]

its a 50*25 if rage is as goos as everyone claims it will do it.in your place i would mind more if the weld will keep it straight,machinist square is your best friend.

 

[FranV8]

You'll spend forever removing metal with a fly cutter.

 

[breezer]

its a 50*25 if rage is as goos as everyone claims it will do it.in your place i would mind more if the weld will keep it straight,machinist square is your best friend.

Yep 50*25*2.5mm

I'm very happy with the rage saw it does exactly what I bought it for - cutting metal reasonably accurately at various angles prior to welding. But the blade can flex a bit - leading to the cut being maybe 1mm out of true over a piece of box as per the dimensions above.

Normally when making any engine stands they have box section laid flat to act as feet, so stability is fine. I manage to keep stuff straight whilst welding by judicious use of clamps.

In this instance though the cut end of a piece of box will be flat onto the bench - hence why it needs to be as square as possible as any angle on the cut will be way out come the top of the workpiece. As I have a few to do I was wondering whether there was a way of doing it quicker and more accurately than hand filing.

 

[MattF]

If you have a lathe, you could easily do a 'bodge' approach and pop some form of hard backed sanding disc, (either a hardwood or metal backing plate), on either a tapered mandrel suitable for the headstock else a straight mandrel held in the chuck, then just clamp the piece to the cross slide and make several passes to grind it flat.