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When making a celtic knot using the cut through method is the thickness of the inserts critical? I watched some tutorials (YouTube) and some say the thickness of the inserts must be the thickness of the cutting blade. Others don't mention the thickness at all but the alignments are not always the best. So what is the rule? Thickness of the blade or any thickness?
The easiest way is to make the inserts the thickness of the cut and only make the cuts partially way through so the blank stays together in one piece at all times.
That has a degree of inbuilt accuracy, which is very important with celtic knots. Mind you, even this method doesn't guarantee that your cuts will be accurate.
Just 0.5mm out when either making any cut or when mounting the blank on the lathe and... :doh:
You can make the inserts as thick as you desire and use other methods, but inaccuracies creep in. Because you're dealing with angles, a small error is magnified when turning and becomes more apparent.
I have successfully made celtic rings with bands of different thicknesses... but have also had a higher 'oh bugger' rate too. :shrug:
Thank you Skew. I want to use the maximum thickness of the wood so I will use the cut through method. I will make a cutting jig for the table saw and a gluing jig to minimize inaccuracies. But you answered my question about insert thickness. Thanks again. BF
I should clarify: each cut does have to be as wide as the insert you want to use for that cut, to keep any previously inserted bands aligned.
eg. If you want to insert a 1cm band, you will need to remove a 1cm wide section from the blank where the band will fit. (NOT 1cm along the length of the built up blank!)
The insert and the removed section (saw kerf) must be the same thickness. As Skew mentioned, if you want a 10 mm band for the knot you must remove 10 mm of the blank, or if you are using a 3.2 mm saw blade with a kerf of 3.2 mm then the inlay must be 3.2 mm thick.
As Skew and Moby have already said, the amount cut from the "blank" MUST equal exactly equal the thickness of the insert, what ever the insert thickness is.Quote:
Originally Posted by Blackforester
Jim
Thank you all for the clarification - much appreciated.
BF
Another thought and another question. When cutting against a stop block and removing more than sawblade width from which end do I remove the extra waste, from the stop block end or the other one? My guess is from the other one, is this correct?
That depends. If all of your bands are going to be the same thickness, then I go that way for safety reasons. (I dislike having the offcut be 'trapped' unless it's clamped securely in some fashion.)Quote:
Originally Posted by Blackforester
For this it can be very handy if you have a system where you can set up two stop blocks, one for each end of the blank, but most home set-ups I've seen for this - including mine :- - don't have the required accuracy of repeatabilty. (ie. errors creep in when flipping back'n forth between stops.)
If one pair will be wider than t'others, then they should be centred at the same point on the blank as the thinner and half the width difference docked from each end.
All inserts will be the same thickness (at least at this stage). What if I insert a spacer between only one stop block and the workpiece for the second cut to achieve the correct spacing and make all 4 cuts this way. This should simulate a wider cutting blade. It looks like I just have to experiment. The two stop block method with secure hold down should also work. I also have CMS and might try it there. Thanks again for all your help.
Quote:
Originally Posted by Blackforester
Use a spacer block against the stop. Make the first cut without the spacer, then insert the spacer for the second cut. Make sure the ends of your blank are square!
Alternate method - use a stop block for each end of the blank, - no spacer required.
SAFETY FIRST - make a sled using two small toggle clamps to hold both sides of the cut!
Yes, i learnt this trick early on. You must put back "only" what you take out.Quote:
Originally Posted by Blackforester
Use a sled and set it to 1 cut, do not change anything, do not move, do not change to do something in between glue ups. keep it the same until all 4 cuts are made. Make a mark on one end of the timber, on all 4 sides and just roll 90deg and orient the same way each cut.
BF, i have just recently posted a rolling pin on here, and it surprisingly turned out spot on. and i say "surprisingly" because the 30degree cuts were not perpendicular, they were slightly off, but as all 4 cuts were the same it all came out in the. If you would like i can post a photo of my crude clamping Jig.
A photo of your jig would helpful.