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Woodworking: Straightening wobbly cuts

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  • dcibel
    started a topic Woodworking: Straightening wobbly cuts

    Woodworking: Straightening wobbly cuts

    Hi all,
    I am sure that I'm not the only one with this problem. I use a straight edge jig with my circular saw to break down 4x8 sheets into usable pieces that I can push through the table saw. The cuts with the circular saw however only seem to be accurate to about 1/16" as the saw is cheap and the blade will cut at an angle slightly depending on where I apply pressure to the handle. I am left with a relatively straight however somewhat wobbly cut, which is unacceptable to push through the table saw.

    I've searched and found a few videos and jigs that can be built relatively easily to make a straight edge so that you can push the stock through the table saw and be left with a clean straight cut. At this point I think the simplest thing to do would just be to get a stick of angle iron or aluminum and clamp it to the board, then use a flush trim bit with my router to straighten the cut. Alternatively take a good straight board and screw it to the stock I want to cut, and use that as a straight edge against the fence.

    I was just wondering what others around here do when breaking down 4x8 sheets to keep a perfectly straight edge. I guess most my problem may be the cheap circular saw, and I should just invest in a better one with a more solid base.

    Thanks.

  • dlr
    replied
    Originally posted by billfitzmaurice View Post
    I have one of those Skil worm drives. It's super heavy duty, but also super heavy. I can't remember the last time I used it. I do all my rough cutting of plywood with an 18v Porter-Cable 6.5" saw, using Freud Diablo blades. I never use thicker than 1/2" plywood, so it has all the power I need.
    I never looked at worm drives before. Amazon listing for this has the new one 1 lbs. lighter then older ones ( of the Skilsaw). There's also a light weight version that looks more interesting for light duty use, also Skilsaw. 18.5 lbs. vs. 11.5 lbs. I'm putting the latter on my wish list, I'm still using the Sears circular saw I bought in the early 80's. Sill running strong, however.

    dlr

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  • robertm
    replied
    Deleted.
    Last edited by robertm; 09-06-2019, 07:41 AM.

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  • billfitzmaurice
    replied
    I have one of those Skil worm drives. It's super heavy duty, but also super heavy. I can't remember the last time I used it. I do all my rough cutting of plywood with an 18v Porter-Cable 6.5" saw, using Freud Diablo blades. I never use thicker than 1/2" plywood, so it has all the power I need.

    Leave a comment:


  • robertm
    replied
    Originally posted by billfitzmaurice View Post
    The resurrection of a three year old thread by a first time poster accompanied by a link to something only vaguely related to the topic very much has the smell of spam.

    On topic, I use one of these as a guide for cutting plywood with a circular saw, and it works as a clamp as well.
    https://www.lowes.com/pd/BORA-Bora-5...Clamp/50092628
    This clamp (or something similar, I have the Tru Grip BB50C) and this worm gear Skil saw for $119 would make a nice set of tools for cutting cabinets. I also like the Diablo blades, a game changer.

    https://smile.amazon.com/SKILSAW-SPT...gateway&sr=8-2

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  • dlr
    replied
    A bit off-topic, but related. I use a router to fix a bad cut and at times make slightly over-sized cuts to an exact dimension, tedious, but it works. Makes perfectly parallel opposing sides, too. I use it to make rabbets as well. Yesterday I was doing the latter with a new Bosch 1/4" straight cut bit, 6mm wide (just under the bit diameter) and 20mm deep. taking 4-5 cuts for the full rabbet. Had been doing that yesterday and the day before on two large woofer boxes on my small table top router with the nearly ubiquitous Black & Decker fixed speed router. I didn't try to cut fast, just constantly. The long term, constant use must have over-heated it. In the middle of a cut, there was a small "snap" sound (through heavy ear protectors), then quiet except for motor noise. At first I thought somehow the bit wasn't tight enough and slipped down, but on inspection the bit had snapped in two, just below the bit blade where the shaft is thinnest. Fortunately, it was underneath the wood. It's still lodged in the plastic dust extractor slot.

    Never had a router bit break before, though I don't do heavy duty woodworking.

    dlr

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  • fpitas
    replied
    i have a few of those too, of different lengths. I like them a lot.

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  • billfitzmaurice
    replied
    What I like about that clamping guide is ease of use, as the clamping mechanism doesn't get in the way of a saw or router.

    Leave a comment:


  • dcibel
    replied
    I have exactly that straight edge as well, picked up for a few bucks at the liquidation store if I recall. I don't use it often, but it came in handy just a few days back to router out a slot port hole. On a budget, a good piece of angle iron and some clamps does the trick as well.

    On the original topic from some years back, I didn't ever get a new circular saw wit a more solid base, but I mostly just use it to break down larger boards anyway, and use my table saw as much as possible as it will cut straight lines very well.

    Leave a comment:


  • billfitzmaurice
    replied
    Originally posted by kiran varanasi
    https://www.consumersbase.com/best-router-table/
    i use this guide to make it better and best way
    The resurrection of a three year old thread by a first time poster accompanied by a link to something only vaguely related to the topic very much has the smell of spam.

    On topic, I use one of these as a guide for cutting plywood with a circular saw, and it works as a clamp as well.
    https://www.lowes.com/pd/BORA-Bora-5...Clamp/50092628

    Leave a comment:


  • dlr
    replied
    Originally posted by Audion View Post
    A question: has anybody tried placing their 4 x 8 board on several 2 x 4's on their driveway, kneel over the board while cutting, staying behind the saw as much as possible?
    I think that this might give a straighter cut because you're over and directly behind the cut line, which avoids some of the sideways forces that occur when you must stand off to the side.
    That's how I have to do it. I use long 2x4 boards aligned with the cut desired. Enough to have support as needed for me to kneel on it and the off cut side to prevent any droop after the saw passes by. Then I clamp on a guide for the circular saw. One big improvement was buying the highest quality blade I could find. Nothing like a good blade in any saw. I even have a vacuum attachment of my own kludge design on the exhaust opening. When the safety rotates so that it's clear, there's not a sawdust blizzard while I cut for the remainder of the cut.

    dlr

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  • dcibel
    replied
    Originally posted by Anji12305 View Post
    It is important to support the works from underneath, fully. If you bridge two tables, sawhorses, or ladders you will induce a vertical curve. We've all seen the videos of CNC routers at play; the large sheets are fully supported by the XY table and clamped down. I follow a similar method using an EZSMart guide and a few clamps to hold the everything together so nothing shifts during the cut. I prefer to cut just below waist height. https://youtu.be/SE8Cjfb7VY8 Sent from my Nexus 6 using Tapatalk
    Thanks for this, the frame built in that video to support the sheet is easy enough to build, I think I even have enough scrap 2x4s to whip it up.

    Leave a comment:


  • Anji12305
    replied
    It is important to support the works from underneath, fully. If you bridge two tables, sawhorses, or ladders you will induce a vertical curve. We've all seen the videos of CNC routers at play; the large sheets are fully supported by the XY table and clamped down. I follow a similar method using an EZSMart guide and a few clamps to hold the everything together so nothing shifts during the cut. I prefer to cut just below waist height. https://youtu.be/SE8Cjfb7VY8 Sent from my Nexus 6 using Tapatalk

    Leave a comment:


  • Millstonemike
    replied
    Originally posted by Paul Carmody View Post
    The biggest culprit are those aluminum clamp-on saw guides. They're just not very sturdy, and the pressure of the saw's shoe against the guide causes it to bend.
    I use angle iron reclaimed from an old bed frame. It is (6.5' x 1.5" x 1/8", possibly x 3/16", I haven't measured it. It does not bend and takes a lot of pressure before it will twist in free air - very difficult to twist it when clamped to a sheet. It's little short for the long run on a 4' x 8' sheet so I need to cut the short side first. The big box stores sell 8' versions.

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  • Paul Carmody
    replied
    I have experienced this as well when doing long cuts. The biggest culprit are those aluminum clamp-on saw guides. They're just not very sturdy, and the pressure of the saw's shoe against the guide causes it to bend. A plain old sawboard made from MDF seems to hold its shape better, so that's what I use now. I see some guys here use an aluminum level--that might work, I don't know if those have any flex in them.

    The other culprit is, as some have pointed out, having the material sag on you. So somehow supporting a massive sheet becomes important as well.

    All that said, I hate breaking down huge boards, and I always let Home Depot or the lumberyard break them into 2x4 sheets for me.

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