What's the difference between the 1/8 collect adaptor and its "precision" counterpart?

How much precision are we talking about?

What is too small for the regular one to handle or handle properly?

Are you only making a joke or implying the only difference really is the price?

I’ve been using a 1/4" - 1/8" collet adapter on my Makita and it’s been OK. One problem I’ve found though is that the adapter limits how far a bit can be inserted into the collet. This can result in a bad finish, chattering and broken bits.
I’ve just ordered some Elaire 1/8" collets.


Thank you for your reply and for introducing me to Elaire collets. I might just get one of those.

What did you mean by a bad finish? Seems like that could describe a variety of problems or I am simply too new to this.

If the bit is sticking too far out, it can flex which can mean wavy cuts or cuts that don’t track as expected/.In a recent job I did in aluminium, the cut was not as clean as expected and I put this down to flex in the bit.

1 precision-machined part w/ a guaranteed runout spec. vs. 1 commodity part plus a second commodity part which are not guaranteed to work well together.

I used an adapter on my Harbor Freight Trim Router, for want of any other option — cuts were much better when I switched to a Makita w/ an Elaire Precision collet — discussion of this on the Shapeoko forums when the latter were first commissioned: http://www.shapeoko.com/forum/viewtopic.php?f=8&t=3445

The two big differences would be clamping and runout. In general they tend to be cheap parts that don’t even have a spec for tolerance. So, they tend to add a LOT of runout and might be tight or loose on both the OD and ID causing clamping issues. A lot of them are also a single split down the side. Since it can only compress in that one direction this single split tends to shift the bit over as you compress it. This generally causes more runout in addition to poor clamping.

If you can’t get good clamping you will end up with the bit or adapter getting pulled out of the collet. This can obviously screw up your finish or if it’s bad enough cost the piece and/or tooling. Poor clamping can also let the bit or adapter spin. This again can cost you your piece/tooling or give you a poor finish.

Another thing to consider is every piece you add between the router and the bit can add runout. This is true even with very tight tolerance parts and each piece has to be accounted for. So as an example lets just say each piece adds one thou of runout (usually both stock collets and adapter are MUCH higher than this). A router->collet->bit setup would add 0.001" runout where the router->collet->adapter->bit would be add 0.002" runout.

Runout is a huge issue with a bunch of complexity. Most know that the runout will effect the size of the cut (adding to the cutting diameter on both sides of the cut). The other thing to keep in mind is runout comes right off the top of your chip load. This added runout will effect both your finish and feedrate as you are having to compensate for the runout in your chip load. On the really bad end enough runout and it could exceed the total chip load of the tool and break the cutter. This is especially an issue with smaller cutters. Oh, and on top of all that you have that whole worse tool life thing…

For obvious reasons I won’t recommend a specific product. But, I hope that at least helps some. If there’s anything I can help with let me know.

Edit: Forgot to address the specific question of what’s too small for one to handle properly.

Unfortunately, there is not good way to answer this. It’s basically going to come down to how much runout is in your collet and how much in in the adapter. Without a spec on them this is a shot in the dark. Could be 0.001" could be 0.010". Oh, and watch for “typical” numbers whenever they do actually list runout. That pretty much means a few were tested and the average of those tested is listed. Obviously this leaves a lot of room for bad parts.

John Torrez
Think & Tinker / PreciseBits



Excellent quality.

NOTE: If you’re using a DeWalt DWP611 router, make sure you use the DWP series of collets (not the DW or DWH series);


My router is the Makita RT0700CX (or something like that).
From previous threads here, the two options for replacement router collets are Elaire or PreciseBits - for the DeWalt at least. PreciseBits don’t make collets suitable for the Makita.

I have the Makita and the Elaire collets. No problems so far, but I can only compare the stock collet to the Elaire - no experience with an adapter.

yea. I typed before looking LOL

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After using the 1/8" adapter with my Dewalt 611 for less than a day, I noticed a ridiculous amount of runout after seemingly every other tool change. Thanks to this thread, I ordered an Elaire precision collet and couldn’t be happier with the upgrade!

Just wanted to say thanks for pointing this out, kind gents.

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Ok, just to verify. I could order the Elari for only 19.50 versus the “precision” for 58.00 from inventables?

go for a real collect and not one of those 1/8th adapters they are safer and wont break your router.