I have a collet nut that will not loosen. at one point while turning the shaft lock button pops up; even when pressed

Inserting the bit should be the same on all versions of the Makita 3612 router. It does depend on the bit size. Press the shaft lock to keep the shaft from turning. I think the lock is close to the handle on one side of the router when you hold the router with the bit/collet up. For small shaft bits, insert the appropriate collet sleeve into the collet cone. Then insert the bit completely into the sleeve. For larger shaft bits, insert the bit completely into the cone. Use the wrench to tighten the collet nut securely. Unlock the shaft lock. Do not over-tighten or leave the bit loose in the collet cone/sleeve. Over-tightening can break the collet cone. Leaving it loose can result in the bit flying out of the collet cone. Either way, injuries can occur. To remove a bit, loosen the collet nut and then remove the bit (or bit and collet sleeve).

The manual is available on the product page: https://www.makitatools.com/products/details/3612 . The direct link to the manual is https://cdn.makitatools.com/apps/cms/doc/prod/361/df12a409-2bd0-48c3-aa38-d635a480a76e_3612_IM.pdf . See page 8.

I hope this helps.

Cindy Wells

The push button used to hold the collet in place whilst the spanner is used to loosen it engages in a slot in the shaft. Rotate the shaft slowly while pressing firmly on the button. If the slot is not located after a full turn of the shaft, the button must have seized. If so, you will need to dis-assemble the router to free it. There are articles on the net on how to do this for most routers.

On some models the collet stays put on purpose. You don't have to remove the nut either. But if you really do have to remove the collet and it is the type that is supposed to come out (maybe you need to use the 1/4 inch collet) then just stick a bit into it without the nut and give the bit a sideways whack with a piece of wood. If the collet has been pressed in tight by the nut without a bit in place, then you won't be able to fit a bit into it, and maybe the collet is ruined. Find the largest diameter shaft you can to fit into the hole and pop that sideways. Good luck.

If you have the standard dremel tool ther is a small bar sticking out at the collet end of tool. This is a locking rod to hold motor shaft in place so you can loosen coollet nut. Put pressure on thebar and slowly rotate the shaft until the bar drops in place. There should be a small open end wrench that comes with your tool to loosen nut. If not use asmall wrench to loosen nut.Turn it counter clock wise to loosen. It is not needed to take the nut all the way off. You may have to move tool slighyly to get it to come out.
The tool that you use is determined by what job you are trying to do.Most come with abrasive cut off wheels small grinders,sanders,and polishers.To secure new tool in collet just insert tool shaft in collet and tighten down. When it gets snug then Depress locking bar to finish tightening. Hope this helps you some. Thank you.

They don't have an instruction manual online at the Black and Decker support site, but if you want a look at the exploded diagram, it's here.

Basically there's a collet nut that gets tightened down to hold the bit in place. You've got to loosen it up and you'll be able to pop bits in and out. You've got to have some way to lock the shaft while you're doing this though.

Most modern routers have a spring loaded shaft lock button. While you're holding it in, start turning the collet. When the shaft gets to the point where there's a little hole for the spring lock, you'll probably hear a little click, and the shaft will be locked so you can loosen the collet. If you take your finger off the shaft lock, it pops right back out again so hold it down while you're loosening and tightening.

If you don't see a shaft lock button, you may have a second hex nut at the base and with two wrenches, you can hold the hex nut and turn the collet loose that way.

If this answer was helpful, please give it a vote. Thanks.

To change bits you should unplug the device.

Turn the shaft while pressing on the lock button located toward the tip of the machine. Turn until lock button is allowed to depress fully.

While holding the lock button loosen the collet nut at the tip of the machine.

Remove the bit you want to replace and slide in the new one.

Sometimes you will have to tap lightly on the top of the bit to get it to release.

You may at times have to replace the chuck to accommodate the different shaft dimensions of some of the bits.

To do this you will have to remove the collet nut completely to remove the chuck.

On my older Sears router there is a lever on the base near the collet nut that you slide to engage the motor shaft to lock the motor shaft for bit changes. On newer models you may have a button or different mechanism to lock the shaft. After the shaft is locked you can use a small wrench to loosen the collet nut, usually by turning it counter-clockwise (viewed from the base). Once the nut is loose the bit should slide out (sometimes the bit is stuck in the collet and the nut may need to come all the way off to get them apart). Just replace the bit with a new bit with the same shaft diameter, tighten the nut, and you are set. If the new bit has a different shaft diameter than the old bit you may need to change the collet also (in general, different collets are used with different bit shaft diameters).

You'll need to use either the built in shaft lock to hold the collet in a fixed position, or use a pair of slip joint pliers to hold the shaft of the bit, while you use the wrench to loosen the collet. Slow and steady should get it loose. Another option is use some penetrating oil sprayed lightly onto the back of the collet to help loosen it from the shaft etc.

slide the orange on/off switch all the way back then push in the black button the switch slides over. This will lock the shaft-then use small wrench provided w/ tool to turn the collet nut

Looking down on the collet end of the dremel, push red button and take pliers and turn locking nut in a counter-clockwise direction.