Rookie dado question for OF 1400

[mwbrewster]

I recently purchased a brand new OF 1400 from Woodcraft and am a little surprised at the trouble I'm having when I try to rout a 5mm dado (6mm deep) in 18mm birch plywood.  Ive watched a series of videos made by someone using the same router, cutting the same dado size, through pre-finished 18mm maple and he seems to be going through the material very easily, in a single pass.

The bit I'm using is a Frued 5mm straight bit.  The cut takes forever and the bit overheats as evidenced by burn marks on either side of the dado, at which time i ease off to let the bit cool.

granted: as a rookie/hobbyist, im sure my technique is ugly at best, but i dont think i'm doing anything to keep the bit from cutting properly.  I'm using the edge guide to keep the router on a true path, and applying even pressure both in towards the dado (on the guide) and along the cut.

Is it normal to have to cut this dado in multiple passes?

Great forum, all comments appreciated.

 

[Bohdan]

As a general rule the max cut depth for any cutter is about equal to its diameter.

Using a 5mm cutter to do a 6mm deep cut is pushing it to its limits and if you want the cutter to give an unburnt clean cut you have to push it so hard that you risk breaking it off.

Try it in two goes and it should work fine.

 

[mwbrewster]

That makes sense. Thanks for taking the time to comment.

 

[AlexThePalex]

Are you sure the bit is sharp enough? 5 mm wide and 6 mm deep is a very small dado, it should not give you any troubles at all.

 

[Cheese]

As Bohdan suggests, I’d tackle this in 2 passes, especially as it’s a straight bit.

 

[mwbrewster]

Alex, brand new bit with the router. thanks

Cheese, thanks, I'll give it a try next time in the garage/shop.

 

[ear3]

You should not be having difficulty cutting a 1/4 deep in a single pass with that bit on the 1400 cutting into plywood.  The concern with cutting too deep with a bit that small wouldn't be so much burning as it would be snapping the bit itself, which I've actually done myself before with a small bit.  I just have to ask, are you using dust collection?  And you're cutting left to right?

Otherwise, I would test out another straight bit just to check the router is ok (preferably one that is a similar size, like a 1/4" straight bit).  Failing that, I would look at the bit and see if it's truly sharp.  I understand that it is new, and I personally have never gotten a dud router bit that was not sharp out of the box from Freud or any other manufacturer, but I don't know what else might be causing the issue.

I only start to get into two pass territory with the 1400 when the dado is in excess of 3/8-1/2" deep (depending on material).

 

[mwbrewster]

Ear3, yes on the extraction and left to right. ill try another bit in a couple weeks when i get back and re-post.  thanks for the advise.

 

[tiralie]

I recently purchased a brand new OF 1400 from Woodcraft and am a little surprised at the trouble I'm having when I try to rout a 5mm dado (6mm deep) in 18mm birch plywood. 

You really shouldn't have any problem going through the Birch plywood with that bit. While birch plywood is a bit more dense than regular ply, it should cut with relative ease at 6mm deep.

The bit I'm using is a Frued 5mm straight bit.  The cut takes forever and the bit overheats as evidenced by burn marks on either side of the dado, at which time i ease off to let the bit cool.

You are moving too slow. Generally a problem with new or inexperienced users. Speed up your feed till you hear the machine motor under load. You will know it when you hear it, then back off the feed rate slightly.

Is it normal to have to cut this dado in multiple passes?

It leads to a better cut, and less splintering on the climb side of the cut. Takes more time, and generally a good habit to get into.
Tim

 

[Cheese]

I really favor spiral cut router bits over straight blade bits.

My first experience was when I happened to have some extra steel end mills laying around and decided to try one in a router. What a difference...the cut and top edge was so smooth. The only problem was that because they were manufactured from high speed steel, they dulled rather rapidly.

The current generation of solid carbide spiral router bits solves this issue. Whiteside, Onsrud, Amana & Freud all manufacture good products.

Here's an article by Pat Warner on spiral vs straight router bits.https://www.woodcraft.com/blog_entries/spiral-router-bits-vs-straight-router-bits

The photo is a 1/4" wide x 1/8" deep plunged dado in maple ply using a carbide spiral router bit from Whiteside.

 

[tiralie]

I really favor spiral cut router bits over straight blade bits.

Agreed, particularly for plywood. If you move too slowly, they will burn too.
Tim

 

[mwbrewster]

thanks again for all the comments. i just ordered a couple whiteside downcut spiral bits for when i get back in a couple weeks.

Incidentally, i went with the 3/16" and 7/32" bits. both undersized - planning on a couple passes - because they didnt have one exactly at 5mm. rather snug than loose for a back panel i assume? then again, would seasonal movement warrant a slightly oversized dado?

didnt plan on a second question, maybe should have started a new thread. hope this doesn't break the etiquette.

thanks again!

 

[thudchkr]

You don’t want your panel to fit loosely. As such, two passes with a smaller diameter bit will let you make the appropriate dado. Your plywood should pretty much remain stable and is not affected by seasonal movement. It is unlikely that even solid wood would move enough, with that small of a groove, to become noticeable.

 

[mwbrewster]

You don’t want your panel to fit loosely. As such, two passes with a smaller diameter bit will let you make the appropriate dado. Your plywood should pretty much remain stable and is not affected by seasonal movement. It is unlikely that even solid wood would move enough, with that small of a groove, to become noticeable.

ok thanks.