Exacto knife tips wanted

[Kurando]

I understand that modelling is mainly about finding things out for yourself and ways that suit you. But I really do need some tips too for using an exacto knife. I also understand it takes practice but some tips would be nice to help me understand better how to use them to make nice clean cuts for things like removing sprues. Even tips like what exacto knives work best ect.

Oh and the kind of exacto knife I use is the type with a big plastic handle with a sliding peice on it to birng the knife out. Also the sharp side is on the oppisite side than the usual pen like scapel exacto knives.

[Blade of the Red Comet]

First off, the retracting kind of Xacto isn't what you should be using. The blade in those is somewhat flexible and can move on you. If you want to strive for accuracy and a clean cut you'll want the kind that looks like a scalpel.
As for removing sprus I would invest in a pair of clippers. I bought one at Home depot for pretty cheap...its actually for stripping and cutting electrical wire but it works very well. I use that to cut off a piece from a spru then delicately slice the rest off with my xacto. When I cut I usually hold the piece in my off hand and, with my right hand, pull the blade against the left over spru towards my thumb. Not very difficult to do really, but you need to be careful cause you can seriously cut yourself if your not. You also need to be kinda slow. The blade is sharp enough to do the work for you, the big thing to be concerned with is safety and the angle of the blade. If you have too much of a downward angle you can mangle the piece.
Sometimes you get some discoloration of the piece but you can also use the xacto to "shave" that area to help blend the discoloration a bit. But if your a painter, then this only would help smoothing out the surface area.

[mttlg]

Cutting technique is something that you just have to develop through experience. Pay attention to how the blade interacts with the plastic and you should figure out where to cut, what angle to cut at, how much force to apply, etc. Also watch how this behavior changes as the blade dulls. You should start noticing a point when the blade no longer cuts through the plastic smoothly; this is when the blade needs to be changed. For best results, you will need to change the blade frequently (I usually transfer the blade to my secondary knife at that point to use for non-precision cutting).

Which model of knife is up to you, but I would not personally recommend anything made by X-Acto. I have found the plastic handle models (like the X-Acto Gripster) to be the most comfortable to handle, but the X-Acto models all lack a 4-way chuck (two perpendicular slits in the part that holds the blade as opposed to one), which keeps them from holding the blade securely enough that you won't need to frequently tighten it during heavy use. My personal favorite is an off-brand knife found at a local hardware store, but it looks to be identical to these:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXNM87
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXL444
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXHE25
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLJ66

It looks like there isn't much variety in the non-X-Acto world, so you may want to try both the metal and plastic versions to see which feels better in your hands.

[Kratos]

Blade and mttlg have got you pretty much covered when it comes to knives, but I'd like to add that, if you're going to use clippers to remove sprus (and I recommend you do), then get a pair that is flat on one side of the clipper blades. This is especially important for removing parts from the runners, as it allows you to get as close as possible to the part without mutilating it.

[Kurando]

Thanks for the help guys. But can somebody show me what kind of clippers in a picture? Mainly because is there much diffrence between using them and nippers?

What I do is use nippers to get rid of most of the sprue and then just cut with the exacto knife.. but usually I either scrape parts I don't want to or sometimes I just can't get rid of the sprue fully and it just remains as a little lump in the plastic.

[Blade of the Red Comet]

Using the nippers first is what you should be doing. But as you'll find out, plastics in these models can have an array of different hardnesses. Some can be stiff and difficult to cut cleanly and some can be relatively soft and easy to cut. After a while you'll find that on softer plastics, leaving a decent sized chunk of spru on the piece will actually help in getting a clean cut.

If I were you, I'd get some practice on some inexpensive kits and move up from there. I got all mine in making WWII fighters back in the day (which was a Wednesday ) and now all I really spend time on modelling is MG's.

Practice, and patience, makes perfect! Modelling is kind of a Zen thing anyways after all.

Ooops...forgot that picture of what I use as clippers. I bought a 2 peice set that had the clipper in the bottom right corner.

[Kurando]

Using the nippers first is what you should be doing. But as you'll find out, plastics in these models can have an array of different hardnesses. Some can be stiff and difficult to cut cleanly and some can be relatively soft and easy to cut. After a while you'll find that on softer plastics, leaving a decent sized chunk of spru on the piece will actually help in getting a clean cut.

If I were you, I'd get some practice on some inexpensive kits and move up from there. I got all mine in making WWII fighters back in the day (which was a Wednesday ) and now all I really spend time on modelling is MG's.

Practice, and patience, makes perfect! Modelling is kind of a Zen thing anyways after all.

Ooops...forgot that picture of what I use as clippers. I bought a 2 peice set that had the clipper in the bottom right corner.

Thanks again!