Hello modelling friends.
One of the biggest problems I have with modelling is sanding plastic parts. No matter how much (or little) I sand / buff I am always left with a slight bump of plastic in the location where the part attaches to the spure. I have been modelling for about 2 years now, however, sanding is perhaps my biggest downfall. In fact, when I am presented with sanding, I get filled with anxiety. I have tried endless different sanding methods with no luck. I have seen some W.I.P pictures here on armorama and planetarmor of unpainted models in progress, one of the things that really stand out is that the locations of spure attachments are non visible even on raw, unpainted plastic model. On my models, I end up with white marks where the spure attachment location and under investigation, the surface is still not perfectly smooth. On armor models it is mostly invisible under paint, however how in the world do you guys get such perfect surfaces for model cars and planes with laquer / gloss coats. If there is any sites you guys know that have some good sanding tips, I would really be thankful if you would share them with me.

Thanks for your time.

I just sand with sandpaper using finer and finer grits.
I'll usually start with an 800 grit at the most. Moving to finer and finer grits until I get the look I'm needing.
When done, that little bit of white sanding dust can be washed off with a bit of good old water. I've never had any trouble with the sprue attachments showing.

Wow.
Starting with 800
I usually start with 200-300 beig very careful not to damage the surface, switching to 400, 600.

A couple of things jump to mind. First thing is - how do you remove the part from the sprue? If you use a razor saw and cut it off the part or at least use a pair of snips/cutters these will make the 'nub' easier to slice down or sand down.
Second thing is how you remove the 'nub' left over. I personally shave it down as much as possible with a Reall Really sharp hobby blade. This leaves very little to sand down.
I also use medium sandpaper first, and only a slight amount. Then I use fine sandpaper.

One last thing that may affect the outcome is the plastic itself. Some kits have softer plastic compared to otheres. I have some older DML kits and the plastic is quite soft and I have to be much more careful with these kits. Tamiya has fairly hard plastic and it's easier to sand harder because the affect isn't as drastic.

I am with you guys on the 800 grit to start, man I would never get anything done :-) As far as sanding tips go, I would suggest using a sanding "block". I use two, a pink trapezoid shaped pencil eraser and a small block of balsa wood. The eraser is firm but also soft enough not to dig into the plastic. The wood I use to make a "true" or square efect on a part. Just wrap the paper around the block and go at it.

I agree that the plastic type has a lot of do with it. I find the current DML plastic to be very easy to work with, but you do have to make sure you don't oversand because it's a bit softer than the others out there. I find Trumpeter plastic very hard and sometimes tougher to deal with - meaning heavier grit sandpaper/sanding sticks to get going.

I bought some sanding sticks of various grits from the make-up section of the local Target and they've worked out really well for me. They're easier to hold that sandpaper, at least for me, and allow me better sanding control.

Like Scott, I try to shave down the nub after using sprue cutters with a sharp X-Acto knife.

One of my bigger challenges has been nubs on rounded parts. I struggled a bit for awhile as I'd tend to flatten one side with oversanding. I've found that cutting a bit further away from the part with my sprue cutters and trimming the bigger nub with the hobby knife, then sanding a little, works better.

- Frank

Thanks for the imput fellas.
I know that sanding is not exact rocket science, however its my biggest downfall of modelling. This topic is usually not even mentioned in modelling books or begginers guides. It seems to simple that noone has really spend the time writing anything about it. My usual sanding sessions are same as you fellas, however I was never happy with my results.
I am just in envy when I see W.I.P pictures with unpainted models with absolutley no evidence of spure contact locations. How do the car building boys prepare such flawless finishes in preparation to gloss ot lacquer paint?
Anyway, if you guys have something to add, or perhaps know a few websites regarding this manner it would be greatly helpful.

Thanks

Martin,
One piece of equipment that I have found useful is the Mission Models Micro-Chisel, the sharp tip needs to be used with care as it can enter skin like a scalpel, but it removes small nubs of plastic beautifully. A little practice at using it is all it needs.

John

Martin,

I haven't done much car building, but I wouldn't be surprised they follow similar techniques as those who build aircraft to be done in gloss or natural metal finishes.

Everything I've read is sand, sand, sand, and sand again, with incredibly fine grits of sandpaper. Then primer, fix the mistakes, and repeat until perfect, then paint.

I know that's beyond the sanding phase like you're asking, but it's all prep work.

One other thing I can add, and it's a take-off of what I posted earlier - sometimes cutting the sprue too close makes things worse. I've found that I have to take a closer look at the part I'm removing to ensure that what I nip it, I don't gouge the part. Sometimes, I've gotten better results with more sprue nub and a hobby knife than cutting too close to the part.

- Frank

Thanks for your ideas.
I was meaning to get one of those Mission Models Micro-Chisel.
They really look first class and I am certan I will find many uses for it.

Thanks

Yah, it sure does take alot longer, but then I'm not too great at getting those last few scratches out of the plastic. I figure that I'd rather take more time up front then use alot of different grades of paper. I actually find that it works pretty well....

The method that works really well for me has nothing to do with sandpaper, in fact I rarely touch the stuff anymore. I use the sprue nippers and cut about 3 to 5 mm away from the part to get it off the tree, then nip the nub down to about 1mm. Less chance of mistakes this way. Then I use a miniature flat file to work the nub down. Like anything else, a little practice and you get really good at it. For parts that are rounded and have attachments inside, again a file, just a round one.

Model on,

Clair

I'm with Clair. I use hobby files. It's quick and always get clean results.

Always snip about 1/8" AWAY from the part(as even sharp snippers or a #11 can sometimes crush large sprue mounts and leave a hole as the plastic running through the sprue is going 'against the grain' flow of the part itself). Always snip smartly as thin part can break from the thickness of the cutter/blade. If its a tiny part like a wire or a very thin plate that the razor can bend, I put the sprue joint over a scrap of balsa to 'brace' the sprue and cut with a single edge razor(thinner and sharper then a #11). You think armor parts are small, try landing gear, tail hooks, horizontal stabilizers, and engine pylons for 1/350 aircraft(80+ on one ship) pieces sometime-let alone windshield wipers My nimitz has over 12,000 parts including pe and only a couple dozen are 'large' You can loose the forklift steering columns pretty easilly considering 10 completeted lifts will fit on a quarter....

Shave the tabs down with a very sharp single edge razor(a couple swipes, not the whole tab at once), and if you have to sand I do it with 400 then 600 sanding sticks(very little pressure). Typically you can do the vast majority of cleanup with the blade and eliminate most sanding-avoiding reshaping the part by accident. Typically if you let the sander do the work and not the pressure, you don't need more then 600 grit for a sprue tab. Sanding invites more trouble then its worth versus a razor though.

Most trouble is from the cross-grain joint being crushed and leaving the scar from cutting to close to the connection point, shaving it makes it 'invisible'. I rarely use #11 blades as the surface is small and not very sharp. You can buy single edge razors 10-1 for the price. If its a huge sprue tab, trim it down against a hard surface, then you can shave the remainder like you're paring an apple.

In the summer time I bought a pair of expensive side-clippers (as this has been recommended 100s of times in magazines, net articles and by friends). When sprues and nubs are cut off, there is practically nothing left. This has speeded up modelling dramatically as well as giving a better and more trustworthy finish. A sharp scalpel removes the rest. If needed, a quick swipe with a needle file, or in visiblabe places, 400 grit wet and dry paper. The sideclippers were expensive but they have been worth every penny. I use the older clippers for removing the plastic piece first from the sprue and only, then, use them.


IMO, this is overkill and un-necessary. Most modern metal is cut with machines that leave a slight pattern in the cut metal and WW2 Russian armor hardly needs a polished end? Having to clean parts starting with 800 grit would kill the fun of modelling for me.

My sprue cutters are a good quality small pair of fingernail side cutters, these have a reverse angle to conventional side cutters and the cutting edge sits up close to the item you are cutting. I then filed the back side of the cutter blade so it is very thin I can cut right up to the part, and fit the cuuter in some tight spots on the sprue if the sprue join is obvious. If it is not so obvious as the gent above said I cut about 3mm back and recut once I can see clearly I then use fine double cut modelling files to trim any small nub left.

Hello fellas.
Wow, there is some great tips posted in this topic.
I would like to thank all of you for your time.
I have also a pair of side cutters (Xuron - considered the best), however, I rarely use it. I have noticed that as Kevinb states, most of the time it will "snap" the spure leaving a scar on the plasic part. I usually will use the cutters to cut the spure runner as far away as possible, and I also use a sharm razor blade to trim closer and closer to the given part. I have read about "shaving" the spure point off with razor blades / #11 blades, however one question remains. How is this exacly done? Do you "slice" the spure point closer and closer, or do you really shave the plastic tab from the top.
I have a good tip to share with some of you. Perhaps it is known to most of you.
When sanding seams / plastic tabs off parts, use a dry erase marker to check the work. On raw plastic, it almost always seems that there is always some inperfections left, but if you ink the plastic at the connection point, (black color works best) or given seam, you will get a good idea how it will look under paint.

Thanks for your imput gents.
Keep the good tips coming.

Kind regards.

Martin

Hi there,

Whenever possible, I would try to press the spruce onto the cutting mat, againm where possible, depends on how moulding make. If not, will cut further away and later trim using the pen knife, then sand.

One point to note, different kit maker uses diff plastic material, so the brittleness will differ (Tamiya vs DML vs Academy!), so you will prob have to experience and get the feel thru practice.

"Slice": Try to slice closer and closer, this is to prevent loss of control and cutting into the part! Then that will be a nightmare!

Great tip with the marker, what i did was to observe the different shade (or shadow at the edge of the bump. I will only stop when the color of the part is uniform.

Cheers!

Hey Gents.
Thanks for all your imput, however problems still persists no matter what I try.
I will try to be as clear as possible, perhaps all of you can try this also and tell me if this happens to you.
After sanding the given part, polish the area of where the contact to the spure was shaven off.
After polishing and looking at it at the right angle, there is ALWAYS the little tab visible when looking at the part in a certain angle on polished plastic.
I have tried everything without any luck, no matter if I sand verticly or horizontally, it always remain there laughing at me.
How would you remove this tiny little bump and get a perfectly smooth finish . Its driving me insane.
Are there any tutorials on the web or websites with good tips?

Hi,

Ever tried scrapping? Basically, use a normal pen knife and scrap the surface lightly, shavings will come off, and this may help solve your nagging problem.

Cheers!