Sloppy morticer help

[Si465]

I recently acquired a cheap (probably not cheap enough) morticer, it does work but seems like it should work better.
Two main issues are the head is sloppy on the columns, and the columns deflect relative to the base.
I think the first problem is the worst and what I seek help for. The carriage has 4 steel bushes that ride on the two columns but there's 0.2mm or more clearance in each one, meaning the head can rotate up and down quite a bit.
The bushes are 30x34, 20mm long (I've no way to check the actual ID).
The columns measure 33.82 with a decent Vernier and don't show any wear - same all over.
I can get new bushes, but suspect they'll not be much tighter than the current ones.
Are there any methods to tighten these bushes, e.g slitting them and shimming behind?

Many thanks in advance

 

[Ollie78]

This is very different to my morticer which has dovetail shaped gibs which can be adjusted a bit with plates and grub screws.
I would imagine that if there was a proper way to adjust the bushings it would be fairly obvious.
It could be easy to make them too tight so they bind.
There may be some slight slop engineered in to it.
As long as the chisel is moving up and down parallel and at 90 degrees to the bed it is fine. As the chisel interacts with the wood then there is a force back through the mechanism as well, maybe its designed with this in mind. The morticer must be "square" when the chisel is actually pushing into the wood.
The column deflecting is a different thing again, I had an old record power morticer that was supposed to be able to use a 16mm chisel but just wouldn't have it, a very sharp 12mm was pushing your luck on that thing.

Just thinking out loud..sometimes it helps !!

Ollie

 

[sawtooth-9]

Replacing the column bushes is not such a big deal - you may need to ream the new bushes to fit the columns, once the new bushes are pressed in.
The biggest problem is that it is a poor design, relying on two columns. This machine probably would not cope with more than a 3/8 inch chisel before the columns will deflect enough to cause a problem.
I suspect there will be two factors in the column deflection
1. The columns themselves are insufficient to prevent "forward / aft" deflection under load
2. It looks like the downward rack operates on only one column - which may result in "twisting"
You could try improving this machine a little but suspect , because of the basic design faults, it's not worth the cost and effort.

 

[Jacob]

Replacing the column bushes is not such a big deal - you may need to ream the new bushes to fit the columns, once the new bushes are pressed in.
The biggest problem is that it is a poor design, relying on two columns. This machine probably would not cope with more than a 3/8 inch chisel before the columns will deflect enough to cause a problem.
I suspect there will be two factors in the column deflection
1. The columns themselves are insufficient to prevent "forward / aft" deflection under load
2. It looks like the downward rack operates on only one column - which may result in "twisting"
You could try improving this machine a little but suspect , because of the basic design faults, it's not worth the cost and effort.

Agree. It looks like a pale shadow of a morticer and very flimsy compared to a proper one. They need to be heavy and sturdy. I'd guess mine must be 100kg or more.
Maybe it'd be useful for light work of some sort.

 

[clogs]

time to move it on I fear.....`Sawtooth is right on all counts...
I regret selling mine....it needed a fork lift to move it....
can't remember the make tho.....grey moment.....

the only way I could see u improving it would be to bolt it down to a heavy bench then attach the comum tops to the wall making sure it's all square.....that will take out most if not all of the deflection ....thats of course if u have room enough....
Heath Robinson I know....
then new bushes custom made, if u take the basic machine to an engineers they could do it easily....
Finding one with time is the problem...
proper mortisers fetch a heavy price now....

 

[Si465]

Thanks everyone, all good points and I know you're probably right that it's a bit too feeble to do it's job.
Ollie your morticer sounds a bit more serious!
After a strip, clean and reassemble properly I've found the columns don't deflect too much surprisingly. This is with a 10mm chisel, agree any bigger is asking too much.
Clogs your idea about bracing against a wall is good, I was thinking of trying this one day.

I have tried slitting the bushes and reinstalling with some drinks can behind as a shim. Ideally I'd have some thinner shim I think (drinks can is about 0.1mm) as it's a little snug on the columns now, but does work better with minimal deflection.

 

[rogxwhit]

You could reduce the amount of shim by not having a full wrap. This could affect the centring though so you'd need to replicate the offset on both columns - ie bias them both in the same direction?

 

[Si465]

You could reduce the amount of shim by not having a full wrap. This could affect the centring though so you'd need to replicate the offset on both columns - ie bias them both in the same direction?

I keep thinking about that, but I think it would mean the bush ends up out of round? Might still work ok though

I keep thinking what I can use for thinner shim, something ~0.07mm thick. Really cheap paper might be that thin but would tear when pushing the bush in I think