blade not aligned with the kerf it just cut

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blade not aligned with the kerf it just cut

Postby meackerman » Mon Apr 06, 2009 8:55 am

So got my JMP all set up, crashed the first blade when I didn't have the piece secure enough and it shifted. replaced that blade, now I find that when I'm cutting, after the blade gets a ways through the wood (3/4" stock), if I pull back off the blade, the blade is no longer exactly aligned with the kerf it just cut. If I lower the blade some what its aligned again, so I don't think the stock has shifted. The blade will realign itself with the kerf even if I don't lower it, so its not off much. But that just seems like another crash waiting to happen.

Near as I can tell the blade is aligned and everything is adjusted like the manual says. I'm also not getting the same quality of cut that I saw John get at the Oakland show, its very good but not the perfection John's JMP was getting.

So what adjustment do I need to recheck? I've been over it a couple times but can't seem to find whats off.
meackerman
 
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Joined: Thu Feb 26, 2009 5:49 pm

Postby John » Mon Apr 06, 2009 9:46 am

Here are the steps/questions I would check to eliminate your experience;

1. Is the blade pinched to the black blade guide (it should be)? If not, adj. the blue blade guide accordingly. (Manual: Step 21)

2. When the keel is loose (unlock both lock knobs fore and aft) does the keel feel firm in the arcuate guides (it should)? If not, you will need to adj. the nylon set screws in the travelers. This can be done without removing the keel--if you have questions, give us a call. (Manual: Step 13)

3. Are your tables slop free? If not adjust (Manual: Step 19).

4. Please completely review Step 22, the most likely cause for your experience.

5. One cause that is not obvious is the kerf in the sacrificial fence. What can happen (remember the blade is 5 human hairs thick!) is the blade cuts just fine until it hits a shoulder in the fence that kicks it left or right. This will cause drift and when you start to re-enter your cut, at best you will hear a faint "click" or at worse the blade crashes! Make sure you have plenty of clearance.

While I am on this subject, here is a trick that I like to employ. On critical cuts where I am dialing in a precise angle, I do this with a large kerf in the fence. Once I am happy with my cut, I will shift the fence and make a clean cut in the fence to the full depth of my final pass. This really works great. Furthermore, it is my experience that minute angular adjustments are almost impossible any other way--Based upon your description, this could be the cause of your experience.

6. This is also not so obvious but it can really cause grief. If you put sandpaper on your trap clamps (we do) do not cut into the the trap clamp. There is only .002" of set in the teeth and if you sand this away, all bets are off for straight cuts.

7. As you experienced, make sure you stock is clamped firmly to the tables at all times.

8. I don't know what wood you are using, but we have experimented with a bunch of them (including acrylics) and if the wood is super hard (i.e, ipe/ironwood), or abrasive (i.e., teak) the blade will dull so quickly that repeatable cuts are really tough, if not impossible. NEVER cut acrylics--trust us.

9. Lastly, make sure you are making passes that allow the blade to cut rather than forcing the stock over the blade. (I am not sure this is relevant to your experience but I am tossing it out there as a reminder.)

We know the blade will track perfectly so we just need to track down and fix the issue. Please keep us posted.

This should work. If not please give me a call-- 1-800-253-3332


--John
John
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Postby meackerman » Mon Apr 06, 2009 10:24 am

definitely get a "click" from the blade aligning itself back in the kerf.

Looks like I have a few things to check tonight.
meackerman
 
Posts: 6
Joined: Thu Feb 26, 2009 5:49 pm

Postby meackerman » Wed Apr 08, 2009 9:07 pm

went through the steps tonight, its better but still a faint "click". got the blade aligned to a few thou.

Seems I need to look further.
meackerman
 
Posts: 6
Joined: Thu Feb 26, 2009 5:49 pm

Postby John » Thu Apr 09, 2009 9:28 am

You are getting closer--and it is completely doable.

One other suggestion, are your cuts fairly effortless? If you force your stock over the blade it can yield erratic cuts. Just a thought.

Double check the keel alignment--that is the typical cause here.

If this persists, give me a call. 800-253-3332

--John
John
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Postby meackerman » Fri Apr 10, 2009 3:07 pm

I have noticed on occasion (not since I did my last bit of alignment) that the piece I was cutting would cut nicely up to a point then get stuck on the blade.
meackerman
 
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Joined: Thu Feb 26, 2009 5:49 pm

Postby Michael » Sat Apr 11, 2009 9:20 am

I have had wood get stuck on the blade when I do not have the wood secured properly to the tables. During the cut, my wood would shift and then bind on the blade.
By clamping a bit better I have avoided it.
Let me know if this is what you are referring to.
Michael
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Postby meackerman » Tue May 05, 2009 10:38 pm

sorry, been kept busy with other projects. laying new flooring, kids birthday you know life.

I haven't noticed that it shifted. When I get back to it I'm going to clamp it with more than the trap clamps and see if that helps.
meackerman
 
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Joined: Thu Feb 26, 2009 5:49 pm


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