Flattening an infill plane
This is probably about one of the most difficult areas in the making of a dovetailed infill plane.
The amount of forces and stresses generated from the peining usually causes the whole structure to convex depending on the force of the peining. The longer the plane body the greater the amount of movement at the centre of the plane. Flushing the dovetails off after the peining will not straighten the plane out. The only way to flatten the sole is with a milling machine, rubbing the sole of a plane on an abrasive surface is not going to work. However most planes will still work if they are not entirely flat, but this isn’t that kind of tool.
After peining, the amount of removal necessary to bring about a flat surface would be far too much for filing or abrading. The abrading system practised by quite a lot of people would only level off the high spots. The pressure applied to the plane to do this will flex the body of the plane to try and match the surface you are pushing against only to spring back once you release it. This usually means that you will still have a plane with a camber or a twist.
The body of a plane can be very difficult for work holding. It would be very expensive to make a jig for this purpose, so for the small number of planes that I make I have chosen to improvise as shown on the above picture. This shows one side open so that the plane can be seen.
At this stage the dovetailing on the sides will only have been partly flushed so that they will stand a little bit proud and I only clamp along this narrow line. There is no contact on the sides but just along the bottom line i.e. dovetail line. The reason for clamping along this narrow line, assuming that there is the usual slight twist, is it will clamp the plane body without changing its shape within reason and this will then allow any twist or deformations to be removed. If I was to clamp directly on to the sides of the plane then I would only change the shape of the plane which would spring back the moment it was released from its work holding jig. Of course the removal of this excess material is done with a very fine cut and the correct tool, no heat must be generated whatsoever.
Although time consuming this system does work and I can achieve some tight tolerances of +/- .0015. This is only a way of removing the excessive material. The rest of the flattening process is another story.
There is no way at any stage I could use a surface grinder on an infill plane as this type of plane is a thin walled box section and as grinding generates heat the structure would be compromised. This would make the whole process impossible.
This is my holding jig shown with the last clamping plate in position.
A picture showing the main parts of an A1 28 ½” jointer but with a long way to go.
Hi Karl,
Many thanks for your blog, I have been an admirer of your planes for a number of years and I’m enjoying reading about how much work goes into each plane you make. A question for you, however I sincerely hope it does not come across as being disrespectful, I am curious as to how many of your planes are used by professional furniture makers as part of their work?
Again, thank you for your time and excellent blog.
Kind regards,
Liam
Comment by Liam — June 29, 2009 @ 1:18 pm
Hi Liam
I do know of a few professional furniture makers who are customers – of course not everybody tells me what their business is.
I know that the biggest percentage of my customers are people in profession such as medical, law and financial.
I do believe that there is a minority who just collect my planes.
Nearly all my customers own more than one of my planes.
k
Comment by admin — June 30, 2009 @ 9:48 am
Karl
What an absolutely fascinating blog. I’ve been a fan of your work for quite a few years now, and this insight into your work highlights the quality and precision that you’re so renowned for.
If I come across any doubtors again, just pointing them at your blog will be sure to convince anybody that your planes offer fantastic value for all the work that goes into them. I’m still not sure how you manage to make a living from this, running a toolroom like that must be a massive overhead.
Keep up the good work and keep blogging.
Cheers
Aled
Comment by Aled — July 1, 2009 @ 11:44 pm
Hi Aled
Your comment is one of those that makes this exercise worthwhile.
You are right to assume it is difficult to make a living from this and no doubt you can see that I am very sincere about the philosophy of what I do. I suspect that since I started plane making there are others making a better living from the bow wave I have created. Any available funds I have are spent on the workshop, leaving me little time/money for marketing, which is probably my downfall.
One of the most important areas of making is the flatness. With the flatness I achieve my planes will cut a thou shaving by pushing the plane along with its own weight and no input. This is one reason that I am holding back from further posting for a week so that my last posting about flattening doesn’t get lost in the archives too quickly.
k
Comment by admin — July 2, 2009 @ 10:28 am
Karl from the blog so far i get the impression you are doing to much ,striving for perfection whilst wearing so many hats.It is hard to admit that whilst being the companys main asset you are also a limiting factor.You only have one pair of hands if you did nothing else you have a maximium of say 1900 hours production per year.
You need help to buy back time for you to do marketing, selling,shows etc.
Three options i can see make less and charge more if your market will take it . Train or take on help but that then makes you an employer with all that entails. Three sub out some of the component parts water jet maybe.
It wouldnt make any difference to me if all components were subbed because with you doing the QA and the fitting and finishing.The finnished plane would be a Holtey which we all know is the best plane in the world.
cheers john c
ps How many parts do Rolls Royce sub contact it is still a Rolls Royce because of there engineering skills.
Comment by John Coleman — July 2, 2009 @ 4:47 pm
Hi John
1900 hours! that’s part time.
Making less and charging more would be a good solution but a bit risky.
Going from a sole trader to an employer I know it will not work.
I am sure that outsourcing wouldn’t work either. The numbers would never attract a subcontractor, and quality will be an issue.
The thing I would like to do the most would be to spend all my time on R&D and let someone else do the manufacturing and that way it would be possible to achieve a high quality at an affordable rate.
k
Comment by admin — July 2, 2009 @ 5:23 pm
Karl 1900 hours is not part time anything more is overtime beware the boss has you brainwashed.Just like to add that is the cleanest looking workshop i have seen since the first year training school at British Areospace Preston in 1976 .Would love to see more pictures of your set up cheers john c
Comment by John Coleman — July 2, 2009 @ 6:25 pm