Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Engineering Techniques and Materials. => Topic started by: wally on January 27, 2013, 08:35:28 pm

Title: Cutting 3mm lite ply with a knife?
Post by: wally on January 27, 2013, 08:35:28 pm
Am I using the wrong tool or am I just weak?!

I've made a start on cutting out the keel and frames for my swordsman of 3mm lite ply and am wondering if I picked up steel by mistake!!!

With a brand new blade in stanley it must be taking 50 passes per cut. At this rate it'll be Christmas.....2014 before i finish!

Any suggestions?

Thanks.
Title: Re: Cutting 3mm lite ply with a knife?
Post by: Tug-Kenny RIP on January 27, 2013, 08:49:04 pm

Perhaps the blades upside down.

Only joking ....   as the Stanley Knife is my best tool.

Plywood, by it's name has the grain reversed several times during the cut, so will be easy going with grain and harder going cross grain.  Something is amiss, as it has NO difficulty going through my fingers.  Exceptionally sharp blades on the genuine Stanley make.  Other blades might bend with excess force, so be careful out there.

Another tip is to snap the tip off by using heavy duty pliers to present more of an AXE strength head for the cut.

Hope this helps

Ken
   
Title: Re: Cutting 3mm lite ply with a knife?
Post by: dreadnought72 on January 27, 2013, 09:00:08 pm
Anything up to 1mm I'd recommend a Stanley Knife. AND a steel edge which you can keep your fingers well away from. (Been there, got the scars and the blood-stained tee-shirt.)

3mm I'd be using a tablesaw (best) or fretsaw (second choice) to do the job. Cut to within a couple of millimetres of the marks, then trim the edges up with a Stanley Knife and sanding blocks.

Andy
Title: Re: Cutting 3mm lite ply with a knife?
Post by: mike_victoriabc on January 27, 2013, 09:14:21 pm
Dremel or other makes - jig saw is handy for ply - not sure if they are still made but I picked up a couple in case at garage sales.
Title: Re: Cutting 3mm lite ply with a knife?
Post by: Tug-Kenny RIP on January 27, 2013, 09:27:18 pm

As this is turning into Engineering tools I have moved the thread over to here


Ken

Title: Re: Cutting 3mm lite ply with a knife?
Post by: wally on January 27, 2013, 09:34:40 pm
Thanks Ken

I think i'll have a go with the jigsaw seeing as i've got one! Was kinda hoping to keep away from the power tools but so be it.

Title: Re: Cutting 3mm lite ply with a knife?
Post by: Tug-Kenny RIP on January 27, 2013, 09:40:08 pm

If you could graduate to a band saw it would produce straight lines much easier. 

I have a fret saw which still has the original blade !!!  couldn't get a straight line to save my life.   %)


If you want to persevere with the Stanley knife then may I also suggest clamping a steel  (thick)  blade to the Plywood  as a safety  net.   It can be done with the Stanley blade but it will take more patience.

Let us know how you get on.

Cheers

Ken

Title: Re: Cutting 3mm lite ply with a knife?
Post by: wally on January 27, 2013, 09:46:23 pm
Didn't really want to have to shell out for expensive tools on my first build so I might fashion some sort of table for the jigsaw to help with the straight lines.

I'm picturing a 25mm piece of mdf with a hole drilled in the centre and jigsaw blade protruding from underneath.....goodbye fingers!





removed quotes as not necessary    :}

Title: Re: Cutting 3mm lite ply with a knife?
Post by: cos918 on January 27, 2013, 09:49:36 pm
For blades have a look at these. Made by Irwin the amount of side load you can put on is imense. I use them all the time. Very sharp and they dont snap there tips.

http://www.ebay.co.uk/itm/Irwin-10-bi-metal-blades-in-plastic-dispenser-/170979350923?pt=UK_Hand_Tools_Equipment&hash=item27cf29d98b

john
Title: Re: Cutting 3mm lite ply with a knife?
Post by: inertia on January 28, 2013, 09:15:54 am
I can cut 3mm liteply with a new Stanley blade consistently with less than six strokes - and I'm no tough guy. Are you sure that you were sold the right stuff? Liteply can be marked quite easily with a thumbnail while birch/marine ply can't. Another test would be to put a scrap piece into hot water. Liteply will delaminate very quickly.
DM
Title: Re: Cutting 3mm lite ply with a knife?
Post by: RMH on January 28, 2013, 09:25:29 am
I agree with Inertia, that's not liteply you are working with
Title: Re: Cutting 3mm lite ply with a knife?
Post by: Circlip on January 28, 2013, 10:05:29 am
On the plans you are working with, "Liteply" wasn't freely available. If you indeed are using a more convential normal grade, don't change it, the weight saving isn't worth the trouble of using wobbly stuff.
 Don't be confused that a "Jigsaw" only plugs into the mains, the original ones are a deep framed Coping saw with a fine blade. Consult Wikkie or Bing or whatever.
  Regards  Ian.
Title: Re: Cutting 3mm lite ply with a knife?
Post by: John W E on January 28, 2013, 04:28:17 pm
hi ya wally - are the plans you are building your model of the swordsman from - the same as those which I used and built the small swordsman in the masterclass ?
aye
john
Title: Re: Cutting 3mm lite ply with a knife?
Post by: wally on January 28, 2013, 05:39:27 pm
Hi bluebird,

Indeed they are. I shall be recording my progress both photographically and verbally. Need to find out if i'm using the right material first!

It was £4.95 for a 300mm x 900mm sheet and has a blue round sticker with Orbit written on it?



hi ya wally - are the plans you are building your model of the swordsman from - the same as those which I used and built the small swordsman in the masterclass ?
aye
john
Title: Re: Cutting 3mm lite ply with a knife?
Post by: colin on January 28, 2013, 06:11:02 pm
Must be showing my age now but time served as a cabinet maker and never known a table saw and a fret saw were enginering tools , just proves never to old to learn.


Regards
Colin
Title: Re: Cutting 3mm lite ply with a knife?
Post by: Circlip on January 28, 2013, 09:36:09 pm
Right  :-))  , Not using the Connolly plans. Confusion over.
 
 Regards  Ian.
Title: Re: Cutting 3mm lite ply with a knife?
Post by: RAAArtyGunner on January 28, 2013, 11:45:37 pm
Must be showing my age now but time served as a cabinet maker and never known a table saw and a fret saw were enginering tools , just proves never to old to learn.


Regards
Colin

Why, you weren't wrong they are woodworking, as are coping saws  %) %)
Title: Re: Cutting 3mm lite ply with a knife?
Post by: colin on January 29, 2013, 05:46:20 am
So why move to engineering and not wood care which includes construction techniques.


Nuff said Colin