1) Five Step Blade Change-Out Process
2) Why the Arbor Bolt Uses Left-handed Threads
Changing out a chop saw blade is a simple process. The main thing you have to remember is that the arbor bolt for the blade has left-hand threads. I will explain later in this post the rationale for why left-hand threads are used.
Five Step Blade Change-Out Process
1) Lock blade guard in upper position
2) Swing spindle cover clear of arbor bolt
3) Engage spindle lock
4) Remove arbor bolt
5) Change-out blade
Pictured below is my Hitachi chop saw that I am going to use for expanding on the above blade change-out process.
Pictured below are the three tools I used to remove the blade.
Blade Change-Out Steps
1 — First get the blade guard raised up & out of the way. I use a spring-loaded clamp to hold the blade guard up. This is shown in the following Photo.
2 — Using a #2 Phillips screwdriver, I next remove the bolt that my screwdriver is on in the above Photo. This allows the Spindle Cover (shown above) to swing down. The Spindle Cover hanging down is shown in the following Photo.
Now you have clear access to the arbor bolt (which holds the blade on).
3 — Next engage the spindle lock. This step will keep the blade locked in place while you remove the arbor bolt. The chop saw Photo below shows the location of the spindle lock.
4 — With a socket wrench, remove the arbor bolt. My arbor bolt head is 10mm. As mentioned earlier, the arbor bolt has left-hand threads. Therefore to remove the arbor bolt, the bolt must be rotated clockwise. And to tighten the arbor bolt, the bolt must be rotated counter-clockwise.
The following Photo shows the arbor bolt being removed.
This next Photo shows the arbor bolt. Note the “L” on the head of the arbor bolt. The “L” indicates that the bolt has left-hand threads.
A close-up shot of the arbor bolt is shown in the following Photo. Note that the threads slant upward going from right-to-left. Handy to know if you need to determine whether a bolt is left-hand or right-hand threaded.
5 — Change-out the blade, reverse the process given above, and you are good to go.
Why the Arbor Bolt Uses Left-handed Threads
I wondered why left-hand threads are used on chop saw arbor bolts. From Googling and reading multiple discussions, the best discussions I found were at car-forum type sites. The best piece of info I stumbled upon was about some vehicles using left-handed threads for tires on the left side of the vehicle. This particular write-up went on to say that the left-handed threads (for tires on the left-side of the vehicle) would counter the nuts from loosening from heavy braking.
Now, consider the following:
1) Chop saw blade rotates clockwise
2) To remove the blade arbor bolt, you turn it clockwise
3) Here’s the answer (for the left-hand threaded arbor bolt), when the blade contacts the wood (being cut) its clockwise rotation is resisted by the wood exerting a counter-clockwise rotational force on the blade. And this counter-clockwise force from the wood is basically working to try to tighten the arbor bolt (that’s a good thing). Remember, you turn the arbor bolt (with left-handed threads) counter-clockwise to tighten.
Knowing how to quickly change out the blade will translate into being more prone to change the blade for special applications that may arise. And knowing the rationale for why a left-handed arbor bolt is used, is just useful to know (I think).
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Until next time, take care