Help with Mortice Chisel

[deema]

Hi All,

I would really appreciate your help and assistance. I am having real problems with cutting mortices with my Sedgwick 571 Morticer. When I make a mortice cut, the chisel seems to 'stick' in the slot making it extremely difficult to retract. (Sometimes pulling the wood out of the vice) Once the first slot is cut, the rest are OK. However, as I cut each end of the mortice first to ensure that the slots remain parallel, its a real pain. I use Clico English style chisels. I sharpen them properly before use using the clico sharpening set. I have checked that the Morticer runs true by placing a clock on the chisel as its brought down in both planes.

I initially thought that this was just the way it is with cutting Morticer, however, recently using the same chisel, and arrangement, I did not experience the problem. I decided to remove the chisel and put it back in again, this time the problem returned. I am now convinced that this must something I'm doing when setting it up.

 

[G S Haydon]

Hi Demma,

What timber are you working with? I don't have great results with the CLICO. I stick with the Japanese style from axminster and they work well. Those sedgewicks are nice morticers. When I trained at college I would always go to the sedgewick because it was simple to set and use. I never had a problem with it jamming.

Have you tried another size of chisel and bit?

 

[Claud1]

Yes I have had the same problem with the same setup but I think I can put it down to being too impatient and trying to cut the mortice too fast and not going for small bites and clearing the chisel

 

[MickCheese]

Try not cutting the first plunge to the full depth, doing the whole slot shallow and then going back to the beginning.

I find if I plunge the first to full depth it can stick.

Mick

 

[Andy RV]

I've had this before, my chisel had a hairline split running from the sharp edge to the cut out for the chippings, it allows it to expand when full of chippings and locks it within the mortice, have a good look at yours.

 

[deema]

Thanks for the really good feedback, I mainly cut seasoned European oak at the moment as I'm restoring my house. I have tried using second hand Ridgeway chisels with the same result. I'll try an Axminster Japanese style.

 

[Jacob]

Try not cutting the first plunge to the full depth, doing the whole slot shallow and then going back to the beginning.

I find if I plunge the first to full depth it can stick.

Mick

Yes that's it - take it down in steps. Also make sure there is enough clearance so it can throw out the chippings.

 

[custard]

I've had the same problem with the same morticer, I think it was due to the drill rubbing the chisel, causing the chisel to heat up and expand. I've found lubricating the drill bit and taking smaller cuts solved the problem. Also, take real care in setting up the machine, if the fence, bed, and chisel aren't all square it can cause jams, and they can all be adjusted with careful shimming.

 

[G S Haydon]

+1 On Jacob with the clearance on any type/brand of chisel & bit. However I have found http://www.axminster.co.uk/harima-japan ... prod22410/ cut so well I have not really needed to keep having bites at the work. We use 12mm mortices most often, I would take it a bit more steady on sizes smaller than 10mm though. The only timber that we struggle morticing is Idigbo, dreadful stuff to mortice. :-(

 

[Phil Pascoe]

I polished the sides of the chisels - that does a lot to stop sticking. As others have said , take it easy on the first cuts.

 

[deema]

Thanks for the help and advice, its really appreciated