Leigh D4 jig - 1/4" or 8mm bits?

[Slavo]

Some time down the track I am thinking of getting the Leigh dovetail jig (money and SWMBO permitting). My question to those who have used one is would you recommend the 1/4" or 8mm bits. Leigh say the 8mm have more strength but are they worth the extra $. I will be using it primarily in Aussie hardwood, such as Syd Blue Gum,
Slavo

[MajorPanic]

Hi ya Slavo

I'd buy the 8mm bits!!!
Having used the Leigh for several years I found that you have to work VERY slowly if you are using ¼" bits on hard timber otherwise they chatter qiute a bit & can cause poorly fitting joints.
I ALWAYS used the 5/16th or ½" up cut spiral bit it gives a MUCH cleaner & easier cut.

[Slavo]

Thanks Major, 8mm it will be when the funds are available. Good tip on using the upcut spiral instead of the straight bit.
Slavo

[hcbph]

If given the choice of using 1/4" without an adapter or 8mm with a adapter sleeve to make it fit a 1/2" collet, I'ld use the 1/4". Happens I have the Leigh D4 and a Bosch plunge router with 1/4", 1/2" plus an additional 8mm collet I picked up. I've has bits slip using sleeves and swore I'ld never do that again. If you have a 8mm collet, go for it. If not, go with the 1/4".

That's my opinion.

[MajorPanic]

If given the choice of using 1/4" without an adapter or 8mm with a adapter sleeve to make it fit a 1/2" collet, I'ld use the 1/4". Happens I have the Leigh D4 and a Bosch plunge router with 1/4", 1/2" plus an additional 8mm collet I picked up. I've has bits slip using sleeves and swore I'ld never do that again. If you have a 8mm collet, go for it. If not, go with the 1/4".

That's my opinion.

If your bits are slipping I'd be looking at your collet and adaptor. You also might want to have a look at the Leigh video and see how lightly a cut is made.
I've used the Leigh for more years than I care to remember as well as taught others how to use it. If bits are slipping there is something wrong with your set-up.
Physics dictates that the more mass you have for the cutter bit the smoother the cut so 8mm bits are going to be better than ¼" bits.

[John Saxton]

Slavo,If given the choice again then I'd also go for the 8mm bits predominately designed to restrict lateral pressure and hence breakage and delineation from the cut.This will aid in using them with the particularly hard timbers here in OZ.

Personally, I have foremostly 1/2" bits but where the 1/4" bits are employed then light cuts are used even on a back-cut where the greatest stress is of paramount concern but with the resultant cut as clean and no tear-out.

Cheers

[maxdangerous]

G'day there,
I picked up a nice set of 8mm bits off Ebay and converted one of my 1/4" routers to 8mm so I wouldn't need to be changing collets all the time.
I only ever seem to pick up the 8mm one now as I seem to get a much nicer finish with it.
Cheers
Max

[mat]

8mm is definitely the go. For the 5/16 spiral upcut I use the Onsrud version from Lee Valley. It has a 5/16 shank which is almost spot on 8mm and fits well in the collet reducer. The Lee Valley is also a good price compared to Carbitool which is also slightly shorter in its cutting length.
I note from another thread that Festool also have a 5/16 spiral upcut with 8mm shank.

[mat]

Slavo
I have bought my bits from various sources. MIK keep most in stock and prices, given exchange rates, are reasonably good + $6 p+p Lee Valley also make a small range (non genuine Leigh) to suit Leigh Jigs at less than $US10 each.

The genuine Leigh bits are made in Taiwan.

If you are buying quite a few bits consider the sets.

[Flowboy]

Hi Slavo,

I also have a D4R and find the 8mm much more satisfactory to use. You get a cleaner cut, particularly in hardwoods. I have used Sydney Blue Gum, Oak, Blackwood and Red Gum and all joints come out clean. I use a Festool 2000OF with an 8mm collet. I like the design of the collet as it does not slip. Also, the soft start is very useful in dovetail making, at least in my experience. I would also suggest a powerful router for the D4R, particularly when you are making large tails in thick timber.
You can get the Leigh bits from MIK, CMT bits from Carbatec (or their own brand which I would use if $ are tight or you are in a bind. CMT actually have a D4R set, in carbide tipped, but they are a combination of 1/4 and 1/2" shanks.
This all being said, if you have a metric jig, you may need to reevaluate the bits you require. With the FMT, though the situation is different, the metric jig needs 6, 8, 10 and 12mm bits, which are far more difficult to find.

Regards,

Rob