How to fit inserts in spiral head jointer?

[Dengue]

I have had a Carbatec 8" jointer model CTJ-350X for 6 months and it is used to dress hardwood mainly. It has a "spiral" head, with 4 rows of 10 inserts each. The inserts are 14.15mm square, with no curvature on the edges or corners. It flattens the hardwood and softwood timber to a very smooth finish, no ridges or trenches, very pleased with it.

Yesterday I hit a small pebble, the size of a small nail head, embedded in the timber, and the result was a raised line the length of the timber, on this and subsequent pieces.

I found the two inserts which aligned with the raised line, and although there was no obvious kink in the cutting edges, I rotated them 90 degrees. This resulted in a wide shallow trench the length of the timber. I then removed the inserts again, cleaned off any gunk with Pitch Rx solution, and cleaned the seating on the cutterhead where the insert fitted. Same result. Concluded that all the inserts needed to be rotated, as possibly the edge that had been used since new was worn down on all the inserts.

Spent several hours today removing each of the 4 rows of inserts (10 inserts at a time), thoroughly cleaning the inserts and the cutterhead seating of each insert, then screwing the Torx headed holding screw back in with a battery drill set to a low clutch torque to avoid excessive tensioning. Was able to loosen the screws with a T20 screwdriver without too much effort, so was happy with the drill - saves a lot of time and effort.

On running a piece of softwood through it, the result was terrible, a series of shallow trenches and raised lines. Some of the trenches were 10mm wide. Typical depth is 0.2mm

Can anyone please suggest where I might be going wrong? I am not sure how to progress. I cannot use it as it is.

[Kuffy]

install the insert and screw loosely into the head. pull the insert away from its home position. use the hand screwdriver to slowly bring the torque up on the screw. the countersink in the screw will aid the positioning of the insert and it will push it back into its home position resting up against the ledge in the cutterhead.

dont use a drill/driver

[Dengue]

Thanks for this information and advice, Kuffy. I followed your advice, and at the same time very lightly smeared the Torx screw threads, the underside of the inserts, and the seats on the cutterhead with light sewing machine oil. Tightening with the Torx screwdriver and the oil made a big difference, but I now have a different problem.

After a pass of 130mm wide softwood on the jointer, I ended up with a single line down the middle. It wasn't really a line, but a step or a plateau, so that half the board was at a certain thickness along its full length, and the other side slightly thinner. Dragging a pencil lightly across the board in one direction results in it stopping at the step. Dragging it lightly across in the other direction and it continues on at the step, as it steps down.

Would anyone have any suggestions on what causes this type of problem, and how to fix it

[elanjacobs]

Now that is weird. Have you checked the thickness with calipers? It could be that the offending insert is slightly skewed, so that one corner is digging in more than the other; this would give you a line only on one side if the insert and 'ramp' back up to the proper thickness which would result in the pencil only catching in one direction.

Sometime's I've had to go back and re-set inserts 3 or 4 times, but they always sort themselves out eventually.

For the record, I always use an impact driver to tighten the screws (4-5 clunks is about right), but when the buzzer has 128 inserts and the thicknesser has 248, hand tightening gets old very quickly.

[Dengue]

I think you might have missed the point, elanjacobs, it is not just one insert. If you look at the finished 130 mm wide board end on, 65mm of it is a certain thickness, and the other 65mm is another thickness

[Kuffy]

I'm assuming the differences in cutting height from one side of the board to the other is tiny, a few thou at best. its not something that could be measured with any great accuracy.

Are you certain that you have rotated all of the cutters to a fresh/sharp edge? Perhaps some are sharp and the other half were accidently installed incorrectly. There will usually be a distinct difference in cutting height and the sheen left on the boards between old and fresh knives.

Have you measured the inserts to be same length, width, thickness and squareness?

assuming the jointer was setup correctly beforehand (outfeed parallel to the cutterhead and outfeed table flat side to side is the important things for this..). you can check to see if it is one or two knives, or half of them as you suspect. Get yourself a straight piece of timber/mdf and mark two lines on it approximately 3mm apart. Lay the board on the outfeed table with the line closest to the infeed lined up with the edge of the outfeed table. Rotate the cutterhead until the knife engages the timber, picks it up and carries forwards by approximately 3mm (you may need to use a custom measurement, 2.4mm, 4.8mm whatever). Do this across the full width of the cutterhead and see where there are any descrepencies. If you are correct that half of the cutters are high and the other other half are low, there will be a obvious change in distance travelled by the timber piece when the cutterhead engages and carries it.

Also, if you have some abrasive or HARD timbers there, run that over the cutters a couple of times. might be that some of the knives have a burr on the edge and the HARDwood should rip it off in no time.

[Dengue]

Hi everyone, thanks for your ideas and suggestions. I am out of action for a few more days after spending the weekend stooped over the jointer

[Kuffy]

did you end up getting it sorted? and did you find what the actual problem was?

[Dengue]

No joy, Kuffy, will be making a fresh start tomorrow or Thursday, depending on how the back pulls up

[mark david]

Hi Dengue,somewhat perplexed by your problem.
While a cordless drill is great for removal of Carbide inserts I do not think they work well for reinserting,if the srews are reinserted to quickly the insert does not always seem to seat 100% correctly and you could crack the insert.
At least that is what I have found when doing mine.You can use the drill to help with re fitting the inserts but it is better to do the last couple of turns of the screw by hand and to make sure the insert is perfectly seated.You can use the drill for final torquing but prefer to do this by hand as you get a better feel for the tightness of the screw.

[elanjacobs]

Wouldn't try with a drill, but an impact driver going slowly works a treat. Done it quite literally thousands of times and I think I've managed to crack 1 tip, maybe 2.

[Dengue]

Well, I have rotated the inserts twice now, and cracked one insert

[Dengue]

The other day I scrupulously cleaned the inserts, the screw threads and Torx head, and the seats on the cutterhead, then with a Torx screwdriver screwed the 40 inserts into place, very lightly oiled with sewing machine oil, all facing the same way, as indicated by the marker letters on each insert (" JT" ). I also blew out the threaded holes in the cutter head using WD40, and then switching the unit on and spinning the cutterhead to clean each hole out centrifugally.

Back into it today. Using the OneWay Multigauge, I measured the vertical distance from the outfeed table level and the body of the cutterhead at Top Dead Centre (TDC) ( see attached photo, ignore indicator reading). The three measurements at the fence, the centre of the table, and the edge nearest the operator measured 48.5, 47.0 and 47.0 thousandths of an inch respectively. I imagine this variation between readings is pretty good, about normal runout on a table saw arbor.

Using the stick method over the cutterhead, initially the stick did not move as I manually rotated the cutterhead, as all the inserts were below the level of the outfeed table, so I then lowered it a bit. I then ran a 130mm wide test piece of pine through the jointer, marked the resultant troughs and peaks and lined them up to find the offending inserts, and there were many. Undid those inserts, and found that some of the screws showed uneven wear on the bevel of the screwhead. So I swapped them around. Didn't make much difference, the finish is still a series of plateaus and troughs as you run your finger across the board. Holding a straight edge across the board, and looking to the light, you can clearly see the light coming through the troughs under the straight edge. Probably a few thou in depth, but quite noticable on the fingers. Didn't have this problem previously.

I then decided to get a bit technical, and measured the vertical height of each of the 40 inserts at TDC to the level of the outfeed table. The results are shown attached, all in thousandth of an inch. I labelled each row A,B,C and D, and numbered each insert in the row from 1 to 10, starting from the fence. The 2nd and 4th rows are offset, and I have shown this in the table attached

You will see that the results are all over the place, indicative of the peaks and troughs I got on the 130mm wide test piece

The first 3 or 4 inserts cut nice and smoothly, they are all pretty even, as shown in the measurements.

The really odd bit about these measurements is that the vertical height for the first 3 or 4 inserts in each row should be the largest number (ie the deepest from the outfeed table level), given that the distance from the outfeed table to the cutterhead body is largest in this region.

There are some curly problems to be addressed too. How do I raise the insert in Row B #5, which shows it is below the level of the first 4 inserts.

I haven't even bothered testing a cut over the last few inserts in each row, just sticking to the 130mm wide test board so far.

Not sure what to do now, hoping someone can help


Multi-gauge.JPG Insert clearances.JPG

[elanjacobs]

Don't know how much help I can be, but here are a few ideas:
Check that the inserts are all the same size and that they're the same size in both directions
Try swapping the inserts around and see if the odd measurements move with them.

I know they might sound a bit silly, but at least you'll know if you just got some dud inserts or a dodgy cutter head.

[Kuffy]

The only thing worth doing would be to raise the operator side of outfeed by about 2.5 thou as it seems to taper off. But then you gotta get infeed coplanar again. As far as the variance insert to insert. It really is a non-issue. The tiny valleys created when flattening boards will be quickly removed during sanding or smoothing/scraping. And your edge jointing processes for glueups, its also a non-issue because mostly panels are glued up sub 50mm thick and you have more than enough perfectly set inserts to cater for a 50mm width cut.

If you are going to continue to try to sort the variances out, I highly recommend not wasting anymore time hand tightening or using a drill. Buy yourself a torque wrench to tighten the screws so that when you measure in thousandths, your not measuring your inconsistent muscles.