Can you use a bit extender with a 2.2kw spindle

I have a 2.2kw spindle for my incoming Forman. I am considering a double thick waist board with screw inserts in the second board. I am not sure I will have the Z travel to accomplish this. If not could I use an extension shaft with collet to give more Z travel?

How would an extension change the travel? It can change position, but not travel. The Z axis has 3 mounting holes to pick from, so you can raise, lower, or use the middle position.

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Your machine shouldn’t be sitting on top of the spoilboard (otherwise it’ll be much harder to replace it when it’s time). But you do want to put blocks under each foot to raise it up to the correct level to work with whatever height your spoilboard ends up at. You shouldn’t need to extend anything nor would I want to. Shorter means less sideways torque.

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Hey Mike,

the traditional Z-16 Z assembly (on Machinist, Woodworker X-35, Woodworker X-50, and Journeyman) always allowed it to drill holes into your machine bed, since it can be attached in three different height positions to the X carriage, as shown here:

The new Z-20 Z assembly now, which is higher and has now 165 mm Z travel (compared to 133 mm on the Z-16) was introduced for the Elite Foreman machine because this machine sits not on Y-35 rails, but on Y-50 rails wich are higher, and the Z-16 would not reach down far enough. The new Z-20 Z assembly has now four different height positions in which you can attach it to the X carriage. I would assume that in the lowest position you can reach lower than the machine feet, just like you can with the previous machines with Y-35 rails and Z-16 Z assemblies.

Since neither I, nor anybody else yet owns a Foreman machine, it’s up to @onefinitycnc to give the dimensions. There is already a thread going on here that tries to guess the Z-20 dimensions.

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I want to thank each of you for your input. I should have been more specific about my true intentions. My concern follows a work around Jay Bates had to do with his Journeyman cart. He had to get a 3 inch long bit to penetrate his double thick spoil board. IF the extender could be used on my spindle no additional bit would be needed. I also want to incorporate a vertical table into my as yet unbuilt cart having the extra length; in this case depth; could prevent unnecessary Z mounting bracket changes when used for a few isolated operations.
So the question still remains.

Hey Mike,

you did not show what you mean with bit extender. If I would ask this question, I would provide a link to the manufacturer’s page with datasheet of the device in question.

But if I imagine what it could be, it would of course be possible to use it, but it would possibly put more horizontal (radial) force on the spindle’s bearings than advisable, especially if you mill sideways and not only drill.

If you want to drill deep holes into your machine bed once, I would simply mount the Z assembly in the lowest position. If you want to work lower than the machine’s feet more often, especially if you want to mill sideways, a bit extender should be prohibitive except if you want to ruin your spindle. In this case you should put your Z travel there where you need it.

Versatile machines in the furniture industry have the possibility to raise and lower the entire X axis, as shown here, that would surely be what you want, but is is difficult to imagine to retrofit this on the Onefinity.

Many people here showed their vertical clamping, maybe you seek their advice. I think they mainly make joints on drawers.

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The extension would not change the travel of the Z axis. It would definitely change the depth the bit could penetrate, which is my objective, with out necessitating fiddling with the Z axis and the inherent tramming issues that would necessitate.

Understood! Adding additional feet under the Y rails raises the both the x and z. It is not about working height above the spoil board. It IS about depth of penetration of the bit into the work piece. The deflection issue is why I have a spindle with 1/2 shank capability, also have the “stiffy” added to the x therefore the Z.

The bit extender is a 1/2in shaft with a 1/2 collet & nut, put this in your spindle/router then your bit in it. They are mostly seen used on router tables. The spindle is a 2.2kw water cooled Huanyang, and yes the bearings are my primary concern. My intention( with the extension) is to do loose tenon joinery pockets on stock short enough to fit the table height. Jay Bates cut actual tenons with the journeyman/Makita combination. Hence my curiosity about the obviously beefier spindle.

Hey Mike,

You did not tell how long it is. You don’t have a datasheet?

You say you have a spindle in order to use 1/2" shank bits because of deflection issues and then you want to use a bit extender, this contradicts itself, if you’re concerned about deflection.

All people here cut tenons with vertical clamping with their Z assembly mounted to one of the available positions. They don’t need a bit extender. Why do you think you need one?

When Jay Bates built a cnc cart for his friend’s Journeyman he used a double waste board that he drilled through both at the same time. He had to get a 3inch bit for the palm router to penetrate both boards together. My thought the extender( used on router tables for top side bit changes) would give more penetration at full Z depth.

Hey Mike,

You could have linked this so that people know what you refer to. I did it for you now.

Now, here you clearly see that this Jay Bates has the Z assembly on the Onefinity CNC on the middle position. You would need no special bit if you simply drill your holes into the table with the Z assembly fixed to the lower position once, and do tramming later when you selected the definitive position suitable for your work. I would ask the vertical clamping people here in which of the three positions they have their Z assembly fixed.

Also a bit extender would surely add much more length than you would need. It could be possible that it’s too long then and that you will have to put the Z assembly into the highest position to even use it.

Regarding your future work with vertical clamped workpieces: Again, all people here cut tenons with vertical clamping with their Z assembly mounted to one of the available positions. They don’t need a bit extender. Why do you think you need one?

By the way, should you really want to mill below the machine bed height regularly, you could buy the new Z-20 Z assembly. It was designed for the higher Y-50 rails of the Foreman machine since the Z-16 Z assembly did not reach low enough. With the Z-20 assembly, you could have your lowest Z travel point even lower than with the traditional Z-16 Z assembly, and this would be with stability.


Also keep in mind he’s using the Makita router which can only be lowered to the plastic housing. If you’re using an 80mm spindle this is not the case, you have near 10" of vertical adjustment of where the spindle is located in the mount.

An extender isn’t going to allow a bit to cut deeper. To get through two layers of a spoilboard you are going to need to use a bit long enough to cut that deep. Otherwise the collet nut will rub on the workpiece.

As for going low enough with a spindle that’s not going to be an issue. Unlike a router you have tons of range. I have mine up almost as high as it can go.

The short answer, to the question you asked, is yes there’s nothing stopping you from using a collet extender with your 80mm spindle.

On the other hand a decent one will run you more than a cheap extended reach bit that you only use a handful of times. As others have said, with a spindle reach is not an issue since there is a huge clamping range. Collet extenders are generally used to add reach and rigidity when using bits in places you physically cannot access with the spindle body, not to increase travel. I’ve designed parts that required 21" extensions on a 5-axis machine out of necessity which is really hard on bearings and clearly not ideal for general use, but technically possible.

FWIW, I did what you are trying to do with a 3" bit in my spindle. I run a 2 level waste board and use alignment pins pressed into my table underneath. Just remember that possible is not always practical, and practical is not always possible.

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Welcome to the forum Alex-E!
Thank you for the concise affirmative answer. My question originated from missing that Jay was using the Makita router bottomed out. He had said earlier he would be using HIS cnc to cut the materials. I did not take in consideration the spoil board had to be cut therefore aligned to the cnc in use.
Your practical/possible reference is priceless.