Mortices and Morticer question

[Woodmatt]

Hi All,

I have a project I am about to start which involves me needing to make about 80 mortices approx 50mmx 50mm x 50mm in some treated softwood.
I intend to use my "hobby" Axminster morticer which I am alway reluctant to use because it's always agro to use.The problem is one, it seems more difficult to drill/cut the mortice in the down direction than I think it should be and secondly when I try to withdraw the bit it always wants to pull the timber upwards including the "retaining bar" that is above the work.

I have considered rubbing some candle wax on the square bit to easy the bit in and out but I am not sure that some of the wax would stay on the inside of the mortice and stop the glue adhering in the joint properly.Any suggestions anyone?

 

[Racers]

50mm forstner bit and a chisel?

Morticers have hold down bars for that very reason, they pull the timber up when you with draw the bit.
If you are having difficulty plunging try extending the drill bit more, use a pound coin as a spacer before you slide the chisel in.

Pete

 

[JonnyW]

I got a small hobby Axi mortise last year and she works away a beauty.

The one I own, has a clamp system that you screw down onto the piece. I've not had problems with the wood lifting.

Have you tried progressing your cuts deeper and deeper as you cut the mortise, starting off quite shallow.

Sorry if I'm pointing out the obvious or teaching my granny how to suck eggs.

Jonny

 

[Phil Pascoe]

Sharpen the chisel well, then go down through the grits of wet & dry and buff up. Make sure there is as little resistance as possible - it's worth the effort. Also make sure you are working with the open side of the chisel to the open side of the mortice.

 

[deema]

If I'm teaching granny to suck eggs, forgiveness is sort!

The bit should project about 3mm below the chisel, a trick is to insert a 2p between the chisel, set the bit flush (actual cutting edge) and then remove the 2p and fasten the chisel into its proper registration.

Check the chisel and the bit are sharp! You should never hone the outside of the chisel if you do it becomes tapered and won't pull out of the wood.

If the wood is pulling up chances are that either the head of the Morticer is not perpendicular or the slides of the bed need tightening up. If the head is not perpendicular in all directions, (I checked with an engineers square laying on the bed and with a chisel mounted in the head) it won't pull out easily.

Check the slides to see if there is any movement sideways at all, that's in the head and the bed. If there is it will move when the chisel is pulled up and trap the chisel.

Cut either end of the mortise first and then clean out inbetween. This stops the chisel wandering to one side due to the uneven pressure and becoming trapped.

 

[Woodmatt]

Thanks for the quick and informative replies everybody,will go check,sharpen and adjust as suggested,thanks again.

 

[Phil Pascoe]

You should never hone the outside of the chisel if you do it becomes tapered and won't pull out of the wood? Mine are deliberately tapered - precisely so they will pull out. Only very slightly, but definitely tapered. I'd have thought they all would be for that reason.

 

[garethharvey]

I have the same issue with my Axminster Mortice machine, have tried new chisels but to no avail. The thing is a nightmare, I now use my router and take out the corners with a chisel later

 

[JonnyW]

Gareth, does the wood ride up when extracting the chisel? It seems strange that you can't get enough clamping force using the wheel/clamp, to stop this happening.

Have you both tried gluing a strip of sandpaper to the faces of the clamp and back fence? A forum member mentioned this trick and it apparently works a treat - I'm yet to do it, but most probably will.

As I mentioned previously, I was always taught to step my chiselling depths to reduce friction when taking the bit out - starting with a very shallow first cut, and I was taught on an industrial powered mortiser.

Having said that, I don't know about other members of this forum, but there is differing schools of thought regarding the cutting of the ends of your holes first. By cutting the ends to their depths first, stops the chisel bending or flexing and gives a more accurate cut through the side of your mortise.

Jonny

 

[wallace]

Is it the machine that has a fork type affair to hold the wood down. The chisel goes between two prongs. Like this one http://www.axminster.co.uk/jet-jbm-5-be ... cer-510315. I had one and couldn't get away with it for the reasons you have. I got something old and heavy with a decent clamp

 

[Phil Pascoe]

I have a small Rexon, which in most respects is a fine little machine (it owes me nothing), but it had a weak cast aluminium hold down. One morning it just went bang. I've two pieces of Alox paper, one one the pad and one on the rear fence - it goes a long way to stopping the piece pulling up but I'm still careful as the bracket the screw runs through is also cast ali and if the wood section is small, the screw is well extended and the leverage is great - and I don't fancy trying to buy a replacement (or having one made) when it breaks. This was the main reason behind my polishing the chisels.
I set the chisel with the open side to the right, start at the right hand side and work towards the left - except I make sure the last cut (to the line) is a whole section of the chisel, leaving any part cut so the chisel can be centred over it.

 

[JonnyW]

Ah thanks Wallace. Sorry I've been talking about a different machine. I have the Axminster Hobby series - AW16BMST2 one. http://www.axminster.co.uk/axminster-hobby-series-aw16bmst2-bench-morticer-501252. It's a lovely little entry machine with an excellent clamp system and side/front/back movement range.

Yep I know the hold down system well. I used to use an add on for my drill press that used the same fork hold-down system. An absolute pain in the rear and worse than useless.

Jonny

 

[woodbrains]

You should never hone the outside of the chisel if you do it becomes tapered and won't pull out of the wood? Mine are deliberately tapered - precisely so they will pull out. Only very slightly, but definitely tapered. I'd have thought they all would be for that reason.

Hello

Tapered which way, though!

Of course mortice chisels can be honed on the outside, and need to be to remove the burrs when sharpening them and to polish them smoother in the first place if cheaper ones have machining marks on the faces. However, they should not be allowed to become tapered towards the cutting tip. It is practical to lap them slightly narrower towards the rear end of the chisel. This prevents them from binding in deep mortices and maintains the chisel size at the business end.

Mike.

 

[dickm]

Dont know if they work better or worse but some Wm Ridgway chisels were only full size for a length not much greater than the width, then reduced by about 1mm for the rest of the length.
Which doesn't help tho OP, but may continue the argument!

 

[Woodmatt]

Yes Wallace that the one I am talking about,the hold down does seem rather a weak peice of metal and could break if put under pressure.I have tried extending the bit as suggested and it does seem a little better.Having done a couple with a forsner bit and chisel as suggested by Pete and it is a better solution for me so I will try again once I have sharpened the square chisel and unless it is markedly better I will then probably resign it to the corner of the shop to gather dust again.

 

[Phil Pascoe]

You should never hone the outside of the chisel if you do it becomes tapered and won't pull out of the wood? Mine are deliberately tapered - precisely so they will pull out. Only very slightly, but definitely tapered. I'd have thought they all would be for that reason.

Hello

Tapered which way, though!

It is practical to lap them slightly narrower towards the rear end of the chisel. This prevents them from binding in deep mortices and maintains the chisel size at the business end.

Mike.

Which is tapering them.

 

[garethharvey]

Gareth, does the wood ride up when extracting the chisel? It seems strange that you can't get enough clamping force using the wheel/clamp, to stop this happening.

Have you both tried gluing a strip of sandpaper to the faces of the clamp and back fence? A forum member mentioned this trick and it apparently works a treat - I'm yet to do it, but most probably will.

As I mentioned previously, I was always taught to step my chiselling depths to reduce friction when taking the bit out - starting with a very shallow first cut, and I was taught on an industrial powered mortiser.

The wood does rid up, I have a small metal U shap which holds the wood down, It just about manages to hold it. It's really annoying, I am convinced it's the machine.

 

[Woodmatt]

Today I have managed to drill out the mortices with my drill press and the forsner bit, now going to square up with a router, template and 6mm cutter as suggested by Neil S.