how do you manually do a 1" roundover?

[mistermikev]

so just daydreaming here about a future build, hope you will humor me.  I want to do something kind of similar to a spector  ns2.  The top and back on that is radius'd.  It also has a large roundover that appears to me to be a hair bigger than 1/2". 

Doing a roundover with a router on something that is already radius'd, esp with a 1/2" roundover bit... it s a bit hairy... esp on figured wood.  I did this on my strat job by placing a flat 3/4" board on top... and hanging the 1/2" roundover low and off the edge quite a bit.  I did have a small choke in my router that is always scary and it took a little divot out of the figured top.  I'm sure if I had to I could simply to small cuts and gradually get down to the half mark, but this type of round-over doesn't follow the profile well anyway.

I have a jig for following the profile for doing binding, but I don't think I'd want to try that with a 1/2" bit on a bigger router... anyway 1/2" isn't big enough. 

Could build a table... but even that isn't going to follow the profile well. 

So I think I'd have to do this manually... but how to be consistent?  Was thinking I might look around for scrapers that happen to feature a 3/4" or larger rounded area?  I guess I could build the profile into a small piece of wood and just check the profile here and there to try to maintain consistency. 

how would you accomplish  1" roundover on top/bottom of a fully radius'd body?

 

[Bizman62]

Some helping lines along the edge might help. Use a depth gauge of your choice for both the side and top to draw the borders of the roundover.

[mistermikev]

23 minutes ago, Bizman62 said:

Some helping lines along the edge might help. Use a depth gauge of your choice for both the side and top to draw the borders of the roundover.

probably couldn't hurt.  right now I'm leaning towards either finding the perfect cabinet scraper, or learning how to make one.

[Bizman62]

5 minutes ago, mistermikev said:

learning how to make one.

Cut a piece of an old saw blade. Don't let it go blue if you use an angle grinder for cutting and shaping.

[ScottR]

You might figure where a 45 degree camber falls within the roundover and cut that first.

SR

[mistermikev]

1 hour ago, Bizman62 said:

Cut a piece of an old saw blade. Don't let it go blue if you use an angle grinder for cutting and shaping.

if I go that route... I will more than likely ask about a thousand more questions when I get there... but I appreciate the info.

4 minutes ago, ScottR said:

You might figure where a 45 degree camber falls within the roundover and cut that first.

SR

well, the chamfer would get me closer... yes, and thank you for the suggestion, but I'm quite hesitant to want to run a router on top of a radius surface.  There isn't as much of the base making contact with the surface so it's precarious at best... esp for running big bits.

Perhaps I should consider trying to build a variation on the binding router.  It just scares me because as you push the body into a big bit... it it decides it wants to pull it in or push it out quickly... and you've got your hands holding it... trouble.

 

thank you both!

[ScottR]

26 minutes ago, mistermikev said:

well, the chamfer would get me closer... yes, and thank you for the suggestion, but I'm quite hesitant to want to run a router on top of a radius surface.  There isn't as much of the base making contact with the surface so it's precarious at best... esp for running big bits.

Oh. I was picturing it on a flat top.

Were it me, I'd carve the bulk of the material away and sand the round over in and let my fingers tell me when it was right. You can go that route and use a template like what's used for a neck profile to check your work against.

SR

[ADFinlayson]

You will be fine with your router jig, just use the climb cutting technique and start off with a much smaller radius and work your way up so you aren't taking much material away in one go. 

[mistermikev]

31 minutes ago, ScottR said:

Oh. I was picturing it on a flat top.

Were it me, I'd carve the bulk of the material away and sand the round over in and let my fingers tell me when it was right. You can go that route and use a template like what's used for a neck profile to check your work against.

SR

good call on the neck profile feeler.

31 minutes ago, ADFinlayson said:

You will be fine with your router jig, just use the climb cutting technique and start off with a much smaller radius and work your way up so you aren't taking much material away in one go. 

I'm sure I would be fine... just seems like sort of a potentially dangerous way to do it and would love to find an easy alternative but I suspect there probably isn't one.

 

thank you both for the replies!

[ADFinlayson]

The other thing, what state are you router bits in? After the catastrophe earlier in the year where my router bit chewed the top on a guitar, I got myself a little diamond and some lapping fluid. Just a couple of passes on each flute and my cheap Chinese round nose bits are cutting significantly better.

[mistermikev]

20 minutes ago, ADFinlayson said:

The other thing, what state are you router bits in? After the catastrophe earlier in the year where my router bit chewed the top on a guitar, I got myself a little diamond and some lapping fluid. Just a couple of passes on each flute and my cheap Chinese round nose bits are cutting significantly better.

crap I'm all out of likes for the day or you'd def get one there... the bit in question was a brand new whiteside 1/2" roundover... but I was using it on a heavily quilted top.  I was only taking off about 1/8" per pass.  had it sitting up on a flat board clamped to the radius... but going out over the horn there wasn't much contact area and I'm guessing I tipped it just a hair.  I knew it was a bad idea when I did it and will take care not to even attempt anything close to that again... that's how folks get hurt.  fortunately I had both hands on the router and was half expecting something so I didn't really flinch... but I recognize it for what it was - not something to repeat.  

all that said.. was just thinking I need to sharpen one or two of my bits.  can you send me a link to what you got?  I realize it's over seas but I'd like to take a look and will snag something similar in the near future.

[curtisa]

3 hours ago, ADFinlayson said:

You will be fine with your router jig, just use the climb cutting technique and start off with a much smaller radius and work your way up so you aren't taking much material away in one go. 

I'd suggest that climb cutting with such a large bit hanging over the edge of a board is possibly one of the most dangerous things you could do with a handheld router.

Bits larger than 1.5" in diameter are generally not recommended for handheld router use. They're just too large to be safely managed at the same RPMs that smaller diameter bits operate at. A 1" roundover bit is likely to be more than 2.5" in diameter once you add the bearing and the extra bit of overcut that the upper curvature of the bit is likely to have. Big bits like that should always be used in table routers or industrial shapers. Even then it's not something I'd personally want to do without some form of mechanical feed/guide system to keep my hands well away from such a large cutter while passing it through.

Climb cutting makes it worse as the bit wants to walk along the rotational direction as it moves along the surface of the timber. The chances of the router wanting to skate off in your hands become much higher, even moreso with such a large diameter bit.

[mistermikev]

1 hour ago, curtisa said:

I'd suggest that climb cutting with such a large bit hanging over the edge of a board is possibly one of the most dangerous things you could do with a handheld router.

Bits larger than 1.5" in diameter are generally not recommended for handheld router use. They're just too large to be safely managed at the same RPMs that smaller diameter bits operate at. A 1" roundover bit is likely to be more than 2.5" in diameter once you add the bearing and the extra bit of overcut that the upper curvature of the bit is likely to have. Big bits like that should always be used in table routers or industrial shapers. Even then it's not something I'd personally want to do without some form of mechanical feed/guide system to keep my hands well away from such a large cutter while passing it through.

Climb cutting makes it worse as the bit wants to walk along the rotational direction as it moves along the surface of the timber. The chances of the router wanting to skate off in your hands become much higher, even moreso with such a large diameter bit.

To be clear: the event I'm talking about was not a 1" roundover bit.. it was a 1/2".  This was on my strat I did a while back.  probably just over 1.375" at the edge.  I've run that sm size bit through solid surface on a flat edge... but a radius edge is scary and not advisable - hence this thread.

Above I was talking about a similar effect with 1" roundover for a future build, but referring back to that experience with a 1/2.   the future build would probably require more like a .75, but even with a variable speed router mounted to a table or overhead jig... I don't think I'd be able to summon the courage to turn that on! 

On that note, I'm not sure table routers are safer than hand held.  It's a false sense of security IMO because the piece can damage you worse than a bit.  (I'm sure you know) a table router can throw a big heavy piece of wood at life threatening speeds, and you typically don't have the same kind of grip of it.  I suspect you probably meant running it with a fence and a featherboard type situation cause I know you know what yer doin', just didn't want to leave anyone reading this thinking that is something they wanna try! 

the most viable option at this point seems to me to be a scraper with a .75-1" radius.  Now... how to get one.

[mistermikev]

in case anyone find themselves in a similar need... was looking around and found this:

https://www.woodcraft.com/products/lynx-2pc-concave-cabinet-scraper-set?gclid=EAIaIQobChMI6OrahbCh5gIVl9hkCh0x0QxFEAQYAyABEgL1tPD_BwE

just what the doc ordered. 

My plan - to try to do this is to do up a photoshop drawing with 22.5/45/67.5 facets.  trace around the outline in the approx intersects from that drawing... use a belt-sander followed by shinto rasp to do the facets... then trace around with this cabinet scraper. 

thank y'all again for your input.