Long bowl gouge grind how?

[gasmansteve]

Hi all
I`m trying unsuccessfully to put a long spindle gouge type grind on my 1/2" bowl gouge. I have been using a 40degree straight across (is that the right term?) grind but would like to try a side grind on the chisel. Its quite a deep fluted chisel so could it be that deep fluted chisels arn`t meant to be used with side grinds or can any chisel be ground with one?. I`m using my spindle gouge jig but set to give 40degs is this incorrect. I`m getting a weird profile on the chisel with the sides going to a rather dangerous point which is just asking for a catch :shock :shock: . I normally grind the chisel like a roughing out gouge just stationary on the grinder but twisting the handle which gives a nice clean edge but this side grind is beating me . Any tips please??
Cheers
Steve

 

[CHJ]

Steve, for starters the deep fluted (Vee fluted) gouges are more difficult to achieve this grind than the shallower (U fluted) ones.

You may find that you need to set your jig to nearer 23-25 degrees.

(The Ellsworth jig is 45deg but this does not work with my jig/grinder and gouges.)

Then move the pivot point further away from the stone so that the front bevel produced is in the 55-60 degree range.

Dependant on your jig you may have to extend the tool protrusion nearer 60-65mm rather than the normal 50mm

The main criteria you are aiming for is that when the tool is at fully over on its side the angle produced by the stone contour is as near the 55-60 degree of the front as possible.

Dependant on the wheel diameter and height above the bench you may have to raise the jig base as well.

I only got near the Ellsworth profile after I had a pre-ground tool to explore all the variables.

 

[Paul.J]

Steve.
I was getting the same problem when i tried the long grind on my Record 3/8 Bowl gouge using the Sorby jig.But yet again thanks to Chas it got sorted.
As Chas says we had to raise the jig 2" and move the jig further away from the stone,which is a 6" stone.
Once the correct angles were found for each gouge we then made a pattern for each to set the jig up at the same angle each time.
Just haven't had the time to try jig out since but am confident that it will work.

 

[CHJ]

Steve, some pics of how much variation I use to get the profiles I prefer.

Apologize for the pic. quality this is not the best time of night to be trying to do this in the shed.

My Ellsworth look alike but with Vee flute not Ellsworth U flute.

Shown with Jig set to 37 1/2 deg. 60mm projection and a spacer/riser block for jig.

This is the critical bit, getting the side angle as near the front angle as possible.

As you can see I have to space my Jig base further away from the stone and lift it to get the required angle on the sides.

Here you can see my Hamlet gouge set up with 50mm projection, Jig angle of 25 deg. and a 1/4" spacer.

My Crown Gouge which is set to 60 deg. bevel for inside base of bowls has to have a 3/4" spacer to achieve similar profile.

The Jig spacers and angle setters for my bowl gouges.

Jig angle and tool projection for my spindle gouge.

 

[gasmansteve]

Chas
Trying to visualize your set up for this type of gouge!. I have a homemade fingernail profile jig (actually a butchered drill sharpener jig) and simply moved the base backwards/forwards until I got 40degs for the front bevel and pivoted the gouge hopefully to get a fingernail profile which it didn`t.Which part of this setup do you mean to set to 23-25degs? is it the angle of the gouge to the base or the jig to the base, how do you then get 55 degs for the front bevel or is that where raising the base comes in?? I`m sure its easier than I`m making it :wink: .
Cheers
Steve

 

[gasmansteve]

Well you beat me to it Chas :lol: Just as I`m typing a reply to you up pops the stuff I`m wanting :lol: :lol: .
Cheers
Steve

 

[CHJ]

Just remember Steve that your Jig head angles etc. will no doubt be different to mine.

The Jig head angle is the main controller of the side angle and the distance from the stone the front angle, quite a few people find that a Jig head angle of about 23deg suits all their bowl gouge requirements.

But this is not a pure science thing because everybodys grinder setup has variables such as stone diameter, centre height actual jig dimentions etc. they all play a part. As do your own actions on time spent grinding on each area of the profile.

It is easy to set up the front bevel angle at any Jig head angle by just moving the jig position relative to the wheel but it would be pure luck if this generated the side profile you require.

 

[gasmansteve]

Hi again Chas
If I want a front bevel of say 50degs am I aiming also for a side profile angle of 50degs to get the long side grind or does the long side grind automatically occur if you get a side angle the same as the front?. I had assumed wrongly that grinding my bowl gouge with a spindle gouge setup would automatically give me a nice fingernail profile like my spindle gouge obviously this is wrong.
My setup simply swings and pivots horizontally about a hole in a piece of wood on the bench whereas yours has the gouge pivoting at right angles to the wheel which might make a difference. Think I`ll have a go making your jig but its slightly different to the two described on your site. All interesting stuff.
Cheers
Steve

 

[CHJ]

...
If I want a front bevel of say 50degs am I aiming also for a side profile angle of 50degs

Yes, that way you have similar feel for the cut as you proceed round the side of the tool, too sharp and a dig in occurs all too easily.

...does the long side grind automatically occur if you get a side angle the same as the front?.

Not quite automatically, you have to watch how much metal you are removing along the sides until you get the profile, but you will never achieve the profile unless the side bevel is near the front bevel.

.... Think I`ll have a go making your jig but its slightly different to the two described on your site.

The Jig is basically the same as the first Jig but with the ability to alter the Jig Head angle and accommodate differing tool shaft diameters.

The second Jig does more or less the same thing, just the pivot point is at the end of the Jig shaft instead of part way up.

I find the form of the 3rd jig reduces the ease with which you can slip off the wheel with the second jig, conversely the 3rd jig does not allow quite so much creativity by the operator on profile.

santiniuk, has made a somewhat swisher looking version of Jig No.3 and is due to post a link to his pictures in the near future.

 

[santiniuk]

santiniuk, has made a somewhat swisher looking version of Jig No.3 and is due to post a link to his pictures in the near future.

Will post pics very soon. It's really nothing special, but it has certainly helped with the quality of sharpening.

Chas, can you do me a favour and take a look on the right hand side wheel on your grinder. I noticed my white wheel was running with vibration so dropped the side cover off to check it was bolted down correctly. On inspection I have noticed that only the left side of the wheel has a metal 'large' washer but on the right hand side the nut fastens down onto the wheel without any washer. Checking the left hand wheel I find the large washers supporting both sides of the wheel.

Thank you.

Shaun

 

[TEP]

Evenin' Shaun, I would be wary of that set up. I've never seen a table grinder that hasn't got a dished washer on each side of the wheel.

Don't know how long you have had the grinder, but if it was me I would be back onto the supplier.

 

[santiniuk]

Totally agree Tam. I was quite shocked when I noticed it wasn't there.

I've had the grinder for about 6 months but it hasn't seen a lot of use to be honest. It was purchased from Axminster so I'm hoping they will be understanding. (Well after last weeks dealings I cannot complain).

Cheers

 

[TEP]

Don't think you should have any problem with Axminster sorting it for you Shaun. After all who opens a grinder, until they have a problem with it of course. Wether they send you a new machine or a washer, we'll wait and see. :lol:

 

[TEP]

Mornin' Steve.

Check out my reply in 'Trouble getting in control' about shaping a gouge tip, it may give some help.

 

[CHJ]

definitely should have a dished spreader washer on there Shaun.

Risk of nut/small washer crushing wheel core without it.

 

[gasmansteve]

Think I`m starting to see it now Tam, When you suggest having the flute flat and grinding off the corners would that be at the same angle to what you want at the front or just the length of side grind reqd. After reading all the different posts I thought there was some magical Jig head angle and Jig stem length that suddenly made it all happen and give the desired shape and it was simply a matter of trial and error. So if I grind off the corners as you suggest that still leaves where to have the bowl gouge in the jig does it not?
I`m sure I`m making this much harder than it should be.
Cheers
Steve

 

[TEP]

Hi Steve. When you grind the corners off just take off enough for the length of wing you want. You don't want them too long. As a rough rule of thumb about 3/8th back on a 3/8th spindle gouge, a little longer on a bowl gouge.

You can set the grinding rest to a approx. angle. ad when grinding check frequently, and keep the grind equal on both sides of the flute. Stop grinding just before the grind gets to the tip. So if you can imagine looking down at the tool and you can see a sharp tip, with a flat each side where your wing edge will be.

Most jigs suggest a projection of 2inches out of the jig front, then use the extension arm to move in and out to get the angle you want for the nose. Another easy way to achieve this is when the chisel is new grind the flute corners off first. Then turn the gouge right way up on the grinding rest and gently grind a small angle face on the tip at the tip about 60 deg. for a bowl gouge. 45 deg. for a spindle gouge.

Fit the chisel into the jig with approx. 2 inch projecting, fit into the arm and slide the arm in or out until the small angle you ground on the nose fits against the wheel.

Lock everything up then slowly grind away at the wings only until you get a edge along the sides. When everything is as near as you can then sweep round from one side to the other. Being careful not to put too much pressure on the tip area as you swing round.

Really the whole thing is slow and easy, and you should get there.

Good luck.

 

[gasmansteve]

Thanks again for that Tam, Excellent instructions, I`ll give that a try tomorrow.
Regards
Steve