How do I know when to stop sanding?

[Fender_Bender]

The lower the grit the more steps you have to take until you get to higher grits where you can jump from say 400 to 600 in one jump. As mentioned, you don’t have to go anywhere near 1200 as long as the scratches from the previous grit are taken care of. Do your best to sand with the grain. Hand sanding with a block with a slightly compliant surface like cork or rubber is your best bet.

 

[byacey]

Get a REALLY bright light, or better yet bright sunlight, and look at it carefully between each grade of paper looking for scratches. If you miss any, the oil will pop them nicely later. Move the bass around and Look at it from all angles in direct, indirect, and raking light.

The best light is low angle light like from a north facing window. The low angle shows all the humps, bumps and irregularities in the surface.

 

[dkelley]

If you can see through it, you already went too far.

Sanding 101

 

[Reedt2000]

You've pretty much been given the right advice already, by folks who've built much bigger and better stuff than me. Light, angles, no need to start so low and end so high, you can wipe on an oil finish so there's no need to pay for it.

I don't think anyone has got super specific about grain filling. If you've got a porus wood, and want a perfectly flat surface after finishing, you've got to fill the pores. I've done this by wet sanding with thinned poly (when I planned on a gloss poly finish), and it can be done with oil finishes. The basic idea is you wet sand with the oil and create fine standing dust which gets pushed into the pores and the oil makes it stick there. Guys like @Scoops have way more experience with the process and would be able to speak more to the finer details.

I'm stoked to see the project. Post lots of pics

 

[Jerammono]

Just a couple things not mentioned. Do not sand the treble side of the neck pocket without knowing the exact dimensions of the neck. This area is critically to the fit of the neck pocket and can be compromised easily.

If it has scratches when you get it or when moving to the next grit, you need to use the same grit that caused the scratches to remove then. 220 will not get 180 scratches out.

The round overs will change with hand sanding. So a radius gauge is a must have if you want to keep it correct.

when sanding near the bottom of the body on the end grain round overs, there is a tendency to leave scratches more easily. Up near the horns too.

If the wood is softer in spots like swamp ash be careful with the sanding pressure. The grain will get rippled pretty quickly. The trick is to use light pressure and use hard sanding blocks where you can. If the grain gets uneven you can fix it by using a higher grit and sand across the grain with extremely light pressure. So if your on 180 grit and the grain starts to ripple grab a piece of 320 grit and lightly sand across the grain until it’s smooth again and then continue with 180 to finish off that grit and remove the cross grain scratches.

Remember the smaller the round over the faster it will lose its shape. The wood comes off quick on anything 1/4 of an inch or smaller.

 

[HearNoStevil]

How do I know when to stop sanding?

When you can see bone.

 

[Plain Old Barry]

The best light is low angle light like from a north facing window. The low angle shows all the humps, bumps and irregularities in the surface.

Yup, a raking light. This is easily duplicated artificially. https://en.wikipedia.org/wiki/Raking_light

Most finishing and auto body shops have low mounted lighting, some portable, some fixtures mounted low on walls for exactly this reason.

 

[MYLOWFREQ]

I wouldn't sand it to 1200 grit if I were to oil it. I'd stop at around 400.

If you have any doubts, let a professional do the sanding, and you do the oiling as someone else said.

And you stop sanding when it smells like chicken

 

[Jerammono]

When you can see bone.

View attachment 3950188

 

[Jerammono]

That really happens when I started sanding bodies full time, I was constantly sanding through my fingertips. My hands were so sensitive to hot water. I couldn’t do dishes. Guess that was a perk.

 

[byacey]

Yup, a raking light. This is easily duplicated artificially. Raking light - Wikipedia

Most finishing and auto body shops have low mounted lighting, some portable, some fixtures mounted low on walls for exactly this reason.

For violins I use a low power 40W incandescent lamp by the workbench in a dimly lit room.

 

[BioWeapon]

Just a couple things not mentioned. Do not sand the treble side of the neck pocket without knowing the exact dimensions of the neck. This area is critically to the fit of the neck pocket and can be compromised easily.

If it has scratches when you get it or when moving to the next grit, you need to use the same grit that caused the scratches to remove then. 220 will not get 180 scratches out.

The round overs will change with hand sanding. So a radius gauge is a must have if you want to keep it correct.

when sanding near the bottom of the body on the end grain round overs, there is a tendency to leave scratches more easily. Up near the horns too.

If the wood is softer in spots like swamp ash be careful with the sanding pressure. The grain will get rippled pretty quickly. The trick is to use light pressure and use hard sanding blocks where you can. If the grain gets uneven you can fix it by using a higher grit and sand across the grain with extremely light pressure. So if your on 180 grit and the grain starts to ripple grab a piece of 320 grit and lightly sand across the grain until it’s smooth again and then continue with 180 to finish off that grit and remove the cross grain scratches.

Remember the smaller the round over the faster it will lose its shape. The wood comes off quick on anything 1/4 of an inch or smaller.

Er, what neck pocket?

 

[funky_chavalo]

Quick update, everyone. After 3 weeks being lost in shipping with no where to be found, my bass finally came up at the warehouse broken in half by FedEx I can’t believe I had to go to the facility myself to pick my bass up (I thought this was a delivery service?) and then as soon as I open it, it’s broken. I expected as much... I’m working on getting it fixed by Steve and having FedEx refund me.
pic below.

 

[Arie X]

Quick update, everyone. After 3 weeks being lost in shipping with no where to be found, my bass finally came up at the warehouse broken in half by FedEx I can’t believe I had to go to the facility myself to pick my bass up (I thought this was a delivery service?) and then as soon as I open it, it’s broken. I expected as much... I’m working on getting it fixed by Steve and having FedEx refund me.
pic below.

that sucks. was it shipped in a gig bag?

 

[funky_chavalo]

that sucks. was it shipped in a gig bag?

No, I put it in my gig bag after. I brought mine with me because I had a feeling it was going to arrive broken.

 

[Arie X]

how was it shipped?

 

[funky_chavalo]

In a foamed up, regular box. The box came broken and with peanuts falling out everywhere. Looks like it was tossed and thrashed around for 3 weeks before I picked it up.

 

[Reedt2000]

Quick update, everyone. After 3 weeks being lost in shipping with no where to be found, my bass finally came up at the warehouse broken in half by FedEx I can’t believe I had to go to the facility myself to pick my bass up (I thought this was a delivery service?) and then as soon as I open it, it’s broken. I expected as much... I’m working on getting it fixed by Steve and having FedEx refund me.
pic below.

Yeah man, that stinks. It is a repair you can do yourself, but probably won't be invisible unless you're doing a solid color finish...

 

[TerribleTim68]

In a foamed up, regular box. The box came broken and with peanuts falling out everywhere. Looks like it was tossed and thrashed around for 3 weeks before I picked it up.

Just a tip here, from past experience shipping fragile plastic classic car grills -
Place said item in a plastic bag, place plastic bag in a box with some air space around it, fill air space with expanding spray foam (that "Great Stuff they use on construction sites works well and is readily available at your local box store). You'll have way less issues with broken things this way.

 

[Arie X]

Just a tip here, from past experience shipping fragile plastic classic car grills -
Place said item in a plastic bag, place plastic bag in a box with some air space around it, fill air space with expanding spray foam (that "Great Stuff they use on construction sites works well and is readily available at your local box store). You'll have way less issues with broken things this way.

well, that's great, but the op was the recipient.