Moulder heads + Rebating

[Louis1984]

Ive just ordered a moulder head from whitehill which will allow me to cut rebates at the same time as cutting an ovolo mould for sash's. I am adamant that the best way round to have them is to have the rebate block on the lower part of the spindle and the mould block on the top of the spindle. He said that is fairly unusual and most people have it the other way round but why?

[katellwood]

Surely the hand of the block will dictate which goes upper

[Louis1984]

I don't understand ...

[katellwood]

Firstly I'm assuming that the block is going on a spindle moulder.

You are correct in that the rebate block can go upper or lower as the grind is symmetrical top and bottom. However the grind on the ovolo blade/block will dictate whether it is designed to cut the ovolo against the bed and the fence (lower) or against the fence on the upper side of the timber. If you invert the block to cut from upper and lower then one of the setups will require the block to rotate in reverse and the timber will need to be fed from the opposite direction

In other words, set up in one way you will have the cutting edge facing the timber feed side however if you turn it over you will have the bevel grind facing you rendering it inoperable

Hope this helps

[katellwood]

Had a play on sketchup which might help explain

This block is how you would normally mount it in a spindle with an anti-clockwise rotation and cutting the mould against the bed and fence



If you invert the block then everything is facing the wrong way and will not cut

[Louis1984]

Haha ok I think I have miss communicated something here and we seem to be veering off course. I totally understand the physics.

From whitehill I have specifically requested that my block sits on top of my rebate block. So I specifically want the rebate at the bottom and mould at the top. Whitehill said to me that people usually go for an underside mould. My question was - Why?

Having the rebate block on the bottom has more benefits in my mind.

1 - weight. Surely you want the heavier block situated lower on the spindle?

2- Sash's. one example I can think of is sliding sash's that have no mould on the bottom rail so you can sit ironmongery on it. All you have to do is remove the TC moulder block and voila, the rebate stays at the same height without the mould.

3 - Waste removal and safety - as the rebate is removing the larger amount of material, surely its safer to have this at the bottom and almost incased by the rebate lip. Having it at the top just seems a lot more unsafe.

Your thoughts welcome

[highbury02]

my set up is ovolo on the bottom rebate block on top.why well as you mentioned
sliding sash windows (know mould on the bottom rail for ironmongery which your talking shite by the way)
should you need to use the ovolo block on its own.
like the meeting rail on the bottom sash has an ovolo and a groove not a rebate.
with your set up you would have to run the ovolo cutter block on top of the material
instead off under it.now i am nearly 61 and Whitehill have been supplying tooling as far back as
i can remember so when the man tells you that everyone else does it the other way round
why did you not take his advise.

[cerdeira]

if you have the moulding block on the top, then slight differences in stock tickness would show up in the moulding side, whereas running the mould underside will reference the material from the spindle table: you'll get more consistent results and it will be easier to smooth the rebated face in case of such slight differences.

[jfc]

Rebate on the top for me also because that's how they came . My cutters are moulding and rebate though so i cant remove part of it .

[Louis1984]

(know mould on the bottom rail for ironmongery which your talking shite by the way)
should you need to use the ovolo block on its own.
like the meeting rail on the bottom sash has an ovolo and a groove not a rebate.
with your set up you would have to run the ovolo cutter block on top of the material
instead off under it.now i am nearly 61 and Whitehill have been supplying tooling as far back as
i can remember so when the man tells you that everyone else does it the other way round
why did you not take his advise.

Bit much.....

I was referring to the bottom rail of the top sash. Why is that "talking shite", by the way?

Whitehill offer, as standard, an option to have the cutter block underneath or over the top. As I said, I have a number of reasons as to why I decided to go for the block on top. Nothing wrong with that. And actually, after reading the perfectly reasonable explanation from cerdeira, I am satisfied that the benefits of having it my own way round, outweigh those of having it your way round.

"now I am nearly 32, and whitehill have been supplying tooling as far back as 3 years, so when the man tells me that everyone else does it the other way round, excuse me for effing asking"!

[Leveller2911]

Just to add my penneth worth but i don't use "all in one" cutters. I have in the past but found that when you run the glazing bars ,on the 2 nd run through (doing the 2nd side of the bar) they can rip the web off the bar especially if the web is down to 4-6mm wide.

My question is if you have a profile block and a rebate block together how can you adust the depth of the rebate?. I do single glazing with 7mm rebate, then 8mm rebate for Double glazing for "slim-lite" type units and then 15mm deep for Duplex type double glazing . It may be fine if every sash you even make is the same rebate but mine aren't...

[Louis1984]

Thats correct you can't adjust the depth. My specific block will only suit a rebate depth of 15mm. I got it to speed up the profiles I do most,

[podengo]

I think that the general convention in joinery is that the face with the moulding is the reference face. That means moulding face down on spindle, down on tenoner and towards fence on morticer.

When marking out the prepared timber, the convex side of a bow is chosen as the moulding face, which then means on a spindle the convex side is down to the bed which means the wood will stay snug against the bed as it goes through.

[Leveller2911]

I also agree with podengo in that the moulding face is usually the reference point . As Podengo states the face/moulding part of the joint is then always nice n snug and any discrepancy in the rebate width can be addressed by sanding.


We all know from experience none of the processes used for making a joint are perfect so morticing,tenoning etc can be marginally out but as long as the moulding part of the joint is spot on then anything else can be sorted out and at the end of the day if the rebate depth is 1 mm out it doesn't matter .If you go the other way and use the rebate side for reference and the joint is not snug you can only sand the moulding face a little before you are sanding into the moulding and if you are out by 1mm on a moulding you will definately notice the difference.

Do other people use vernier gauges when setting up ?.

I sometimes think I'm a bit anal with measuring....

[Jonathan]

Leveller, I agree with what most are saying, face side down on bed.
I use one of these gadgets I knocked up to measure head height and depth.
I also suffer from the perfectionist disease....

[Louis1984]

I'm slightly different in thought when it comes to a slightly bowed timber....

I don't necessarily go by the rule that the mould goes on the concave side.

For example - Say a door stile is slightly bowed (an internally opening door), I reference it so that the concave side closes into the rebate. Thus intending the the lock/latch/lever with hold the stile straight until the timber naturally straightens out

I try to have fresh cutters for each job, I don't think i've ever had a 1mm difference in timber thickness. but I will also generally try to avoid timber that has a lot of movement. Sapele is probably the timber which seems to move / swell the most (from what I use)

[Louis1984]

I'm still satisfied that my reasons for choosing a top moulder block are right for my circumstances. If i'm proven wrong well so be it. I'll just fork out again and you live and learn.

I'm certainly not going to blindly listen to one salesman on the phone, and presume he knows what's best for me

[Leveller2911]

Leveller, I agree with what most are saying, face side down on bed.
I use one of these gadgets I knocked up to measure head height and depth.
I also suffer from the perfectionist disease....

I Made up a similar vernier type jig as yours Jonathan and it works well. With the best will in the world we still have to rely on the machinery and our Morticer has a certain amount of "creep" in the bed which we regularly adjust the bed but its not perfect.

Drives me up the wall when you have a 200mm wide mortice and theres a 1mm or more in difference from one end to the other but we cope.....

[Leveller2911]

I'm slightly different in thought when it comes to a slightly bowed timber....

I don't necessarily go by the rule that the mould goes on the concave side.

For example - Say a door stile is slightly bowed (an internally opening door), I reference it so that the concave side closes into the rebate. Thus intending the the lock/latch/lever with hold the stile straight until the timber naturally straightens out

I'm not saying the mould has to go on the concave side Louis it can go on either side. First thing I do when I'm setting out is mark the face and an edge but at this point I decide on which side/edge will have the rebate too .

This doesn't stop me making the moulding(face)side and (face) edge the reference point so that face/edge always sits on the bed of the machine and against the fence.The face I intend to mould sits against the morticer fence and it then sits face down on the tenon cutter.This way any discrepancy is in the rebate which can then be sanded and if the rebate width is different from the top of the doors to the bottom of the door by 1mm or so it won't make any difference but the moulding,scribe will always be spot on.


If I'm making a single door I make the bow/concave on the hinge side so the middle hinge straightens the stile.If I have a pair of doors and its one of the wider meeting stiles thats bowed I also use the locks to hold the door shut in the middle against the AQ21 fitted to the adjacent door

None of this stops me from moulding the face marked side/edge.

I'm not the best at explaining what I mean when writing it down......

[ja2_k]

Just set my blocks up ready for the morning. All whitehill

[woodcarver]

The question was raised earlier, how to adjust the depth of rebating when stacking blocks and moulding in one pass, I know Whithill make many different ovello cutters , but some times of depth is required. The only way I have come up with is using a serrated block for the rebater and adjust the depth on the serrations. Does anyone else have any other way of doing this?

[podengo]

The simplest way to achieve different rebate depths is to machine profile and rebate seperately.