Problem with Silver line dovetail jig and Bosch advance trim router

[Richard The Fifth]

I am trying to make dovetail joints as a complete newbie to woodworking. I have a silver line jig and a Bosch Advanced trim router and a range of sizes of dovetail jig bits. No matter what I do my joints are sloppy. Tried raising and lowering the bit etc. I think I know what the issue is, but the fix will involve £££’s so wanted to check first...

The jig is 1/2 inch has spaced finger guides. The router guide is 12 mm meaning the router has some movement in the guide. If I go down one side of the guide I end up with a joint tight on one side and loose on the other. If I go down one side of the guide and back up the other side I end up with a joint loose on both sides!

The think the issue is a 12mm router guide in a 1/2 spaced jig, but.... no one seems to make a 1/2 guide for a Bosch 18v-8 advanced trim router, and the trend universal base plate doesn’t fit it.

Is this the issue? Or is there another fix / issue? Do I need to buy a different router that accommodates a 1/2 inch guide?

Kit
Bosch Advanced Trim Router 18v-8
Silver line Dovetail Jig
12mm MDF
Complete Noob!

Thanks

 

[Rhossydd]

Those photos suggest that the depth of cut is too shallow.
However if the guide bush doesn't snugly fit the jig and the cutter isn't properly cantered you're unlikely to ever get decent results.

 

[Tris]

A set like this may be the answer. It's been a while since I used a dovetail jig but I do recall having to use a bush to get the correct clearance for the dovetail cutter being used.

https://www.amazon.co.uk/KATSU-Rout...t=&hvlocphy=9046184&hvtargid=pla-819821598615

 

[Richard The Fifth]

A set like this may be the answer. It's been a while since I used a dovetail jig but I do recall having to use a bush to get the correct clearance for the dovetail cutter being used.

https://www.amazon.co.uk/KATSU-Rout...t=&hvlocphy=9046184&hvtargid=pla-819821598615

Thanks - Sadly they don't fit my router

 

[Tris]

If I'm looking at the right model it appears there is a circular plate screwed to the square base. You could possibly make an MDF or perspex sub base with a hole to suit the katsu kit and screw it on in place of the existing perspex circle

 

[Essex Barn Workshop]

with katsu, it's usually best to go to the importer, same thing here at £18.99
https://www.aimtools.co.uk/products/105436?_pos=1&_sid=80cec01d7&_ss=r

 

[Jacob]

Do it by hand and just use the router to pop out most of the waste.

 

[Rhossydd]

Thanks - Sadly they don't fit my router

Not only that, the correct size isn't included.
Looking at Silverline's instructions; you need a 7/16th guide bush (11.1mm) it's presumably made for the US market. Which seems to be at variance with your experience too.
Get the depth right first, then try to work out where the error is. You might need double passes with a smaller guide bush.

 

[Stevekane]

If I'm looking at the right model it appears there is a circular plate screwed to the square base. You could possibly make an MDF or perspex sub base with a hole to suit the katsu kit and screw it on in place of the existing perspex circle

But he already has a 12mm bush,,he needs a 1/2ins,,or have I completly miss-read it?

 

[Rhossydd]

But he already has a 12mm bush,,he needs a 1/2ins,,or have I completly miss-read it?

That's what the OP has said.
The difficulty he says is getting a 1/2" guide for the router. It may be possible to wrap the 12mm guide bush with tape to increase the diameter as an emergency fix, but that would be far from ideal.
It also might be possible to make a complete new baseplate that would take a 1/2" guide bush, but they don't seem easily available in the UK.
I think the best advice it to contact Silverline and ask how it's meant to work and see what they say.

 

[Tris]

But he already has a 12mm bush,,he needs a 1/2ins,,or have I completly miss-read it?

No, I did! Should have linked this one: https://www.amazon.co.uk/POWERTEC-7...2673&sprefix=inch+router+bush,aps,171&sr=8-27

Think a 12mm cutter with a 12mm bush would work, but can't find one of those either

 

[HamsterJam]

I had a similar issue where I needed non-standard guide bushes to fit my POF500 router. I resolved it by using a smaller guide bush and fixing sleeves to it.
I 3D printed the sleeves but other methods and materials are available.

 

[MikeJhn]

Leigh make an adjustable guide bush for their Dovetail jig, could solve the problem?

https://www.axminstertools.com/leigh-elliptical-guide-bushes-ax826784

 

[Stevekane]

Leigh make an adjustable guide bush for their Dovetail jig, could solve the problem?

https://www.axminstertools.com/leigh-elliptical-guide-bushes-ax826784

They do a 12.7mm (1/2ins) but the few reviews are terrible.
I wonder if you could find one on the american ebay site, some sellers are quite happy to post to the uk and small items are not too dear to send I think. The only other thought was I wonder if one of the clever people on here could 3D print one for you?
Steve

 

[MikeJhn]

Leigh make an adjustable guide bush for their Dovetail jig, could solve the problem?

https://www.axminstertools.com/leigh-elliptical-guide-bushes-ax826784

I could not fault the Leigh adjustable guide bush, it made setting up much easier if you knew how to use it. Available through Axminster in the UK as are the RR of Dovetail jigs.