Grinding Wheels For The Great Machine
Happy Gerald


Grinding and Buffing Wheel for the Great Machine


Now that I have created the motor, or the tread-wheel portion of “The Great Machine”, I am working on a brake to control it, the main drive shaft, and something for it to run. One of the simplest useful tools I can think of is a grinding and buffing wheel machine.
Fig 1 Luttell Psalter.Fig 2 16th C Pedal grinder.Fig 3 My Pedal Powered Grinder.Fig 4 16th C Water Powered Grinders (Stradanus).Fig 5 16th C Water Powered Grinders (Mendel Brothers).Fig 6 My Pedal Grinder.Fig 7  Grinding Wheels I Have Collected

Theophlis (from about 1100 AD) talks about smoothing file blanks on a grinder before cutting the teeth1. Earlier grinders seemed to be hand cranked like the example pictured in the Luttell Psalter, Fig 12. Note the large size of the wheel. I have seen some pictured as if they were twice this size where the grind man worked from the top of a large frame. Perhaps they were adapted from used mill stones.  Leonardo da Vinci drew a pedal powered lathe in the late 1400’s3 and we see a similar adaptation to the grinding wheel in 1570 fig 24.  Pedal power seems to be a later adaptation perhaps contemporary with attaching these machines to water and tread wheels.  I can’t say for sure weather pedal power existed earlier than Da Vinci or not.  Agricola in 1556 had woodcuts for pedal powered bellows along with many manual, water, and tread-wheel powered versions.5 I built a pedal powered grinder of old pedal grinder parts, see Fig 3.6  It is “fixed up” with modern hardware but designed to be in form and function like the one in Fig.2.  The original parts were beyond restoration and I was not interested in rebuilding the entire framework and bucket of wood.  I wanted the experience and capability of using a pedal powered machine and thus discovered it is difficult to hold a part steady while pedaling at the same time.  I wanted both hands and both feet free to control the part and more power!

Leonardo da Vinci lists knife grinding and sharpening, as well as burnishing arms, among the things that water power could be used for if the Arno River could be rectified.7 The grinders and polishers Leonardo had in mind were probably similar to the ones pictured 100 years later shown in Fig. 4.8 and Fig.5.9. A smaller system of this design would be perfect for The Great Machine. Note the large size of the wheels in Fig. 4 & 5.  They look to be about 3 or more feet in diameter.  The polishing wheels in Fig.5 appear to have some sort of applied surface such as a thick felt or leather belt to hold polishing compound.  Contrast these to a modern buffer as shown in Fig. 610 which has only a 6 inch wheel (See soda can for scale.) and is made of pieces stitched together Although some modern buffing wheels are a bit larger than the one shown, they go on motors that are designed to run slower.

The large wheel size was important for the medieval grinders to work properly.  Modern machinist will talk of “sfm” meaning “surface feet per minute”.  This number can be calculated by multiplying the circumference in feet of a cutting tool (buffing and grinding wheels are considered cutting tools) by the revolutions per minute that its motor turns. Each type of tool and material has an ideal sfm that it machines best at.  For grinding and polishing wheels, it represents how much grinding surface goes past the object being ground or polished in a given amount of time.  Too much speed heats up and or burns the metal while too little is simply slower and less efficient.  The 6 in. modern wheel above runs at 1725 RPM on its ¼ Hp motor or at about 2700 sfm.  My dogs run their wheel about 20 RPM and I plan on gearing that up to 60 RPM on the main drive shaft.  I originally planed on making a 28 in. buffing wheel from material sewed together from old blue jeans.  (The 28 inches is about as big as the material will allow.) The 60 RPM gives a sfm of 440 fm or only 1/6 the sfm of the modern wheel.  A 3 foot diameter wheel would bring the sfm up to 565 sfm. If the water wheel turning the toothed gear in the period picture goes about the same speed as my dogs then I would estimate from the gear diameters that the shaft rpm would be about 100 RPM and the biggest wheel at about 2/3 the height of the workers.  Figuring the workers at 5.5 feet tall gives an estimate for the largest wheel of a sfm of about 1150.  Running my 28 in. buffing wheel at two and a half times the mane shaft speed would put my sfm at about 1100, or similar to the large sized wheels in the picture.  If I made my wheel 3.5 ft in diameter then the sfm for 60 RPM is 659 and 1320 if it were doubled. The sfm would be 565 or 1130 for a wheel only 3 ft in diameter The bottom line is that doubling the speed from main shaft to grinder should make my machine run at about the same sfm as the medieval one. It is worth noting that there are wheels of different sizes in both medieval pictures. It is unknown weather this is because some of the wheels are partly worn or weather it to make allowances for different sfm applications. The sfm works out to be about 40% of the modern version.  For comparison sake I timed myself as if I was hand buffing with a 6 inch stroke at 165 strokes per minute.  That’s about 330 sfm figuring as if both stroke directions would be equally effective.  This would be a pace that would be impossible to keep up more than a few minutes especially when a little more pressure is used.  It is only about 12% of the modern buffer and 30% of the period machine.  So the period power buffer would be 3 times faster and far more sustainable than hand buffing. It would be a very effective tool even if not up to modern standards.  I have the option of gearing up the buffer to go faster and I may try that eventually but there is a limit to how much speed or RPM the period bearings can handle before heating up with friction or getting wobbly due to balancing issues.  Large wheels running at slower speeds were the medieval solution.

Fig 8 Sketch of Buffer-Grinder set-up...Fig 9  Lathe and Barrel Tumbler Adaptions...Fig 10 Diderots Barrel Tumbler
By careful design I can use the same framework for grinding and buffing, or to rotate a wine barrel for tumbling and polishing chain mail or by adding a rail, head, and tail stock to create a lathe.  My system is small enough that it probably won’t be able to power as many wheels as is shown in figures 4 and 5.  I therefore will only set it up to run a few..  I plan on designing it so that pulleys are interchangeable as well as the grinding and buffing wheels.  Eventually I hope to be able to have several buffing wheels with different grits and abrasives.  I have collected several large grinding wheels from broken peddle grinders which I wish to use.  See Fig. 7.  See Figs. 8 and 9 for some undimentioned but roughly to scale drawings of what I plan for the grinder-buffer and the barrel-tumbler and lathe attachments.  Fig 10 is an 18th century hand cranked barrel tumbler simular to the one I have in mind.11 It was used in processing leather, but such a tumbler has many uses.



1 Theophilus 1979, 93

2 Backhouse 2000, 37 909 9 (F.78 verso of Luttrell Ssalter)

3 Reti and Dibner. 1969, 51 Originally From Codice Atlantico di Leonardo da Vinci (C.A.,fol. 38LR)


5 Agricola 1950, 211

6 Authors Photo

7 Reti and Dibner. 1969, 90 Originally From Codice Atlantico di Leonardo da Vinci (C.A.,fol. 38LR)

8 Stradanus, (1580's)

9 Price 2000, 264 (From Hausbuch der Mendelschen c.1571)

Authors Photo

11 Diderot 2002, pl vi



Citations For Grinder


Agricola, Georg, Herbert Hoover, and Lou Henry Hoover. 1950. De re metallica. New York: Dover Publications.

ISBN0-486-60006-8 LCCCN A51-8994


Backhouse, Janet. 2000. Medieval rural life in the Luttrell Psalter. Toronto: University of Toronto Press.



Lindahl, Greg (editor) Medieval Renaissance Food Homepage (Italian Kitchen) (Pedal Grinder)


Price, Brian R., David Edge, and Alan Williams. 2000. Techniques of medieval armour reproduction: the 14th century. Boulder, Colo: Paladin Press.

Recueil de planches sur les sciences, les arts libéraux, et les arts méchaniques, avec leur explication Arts du cuir. 2002. [Paris]: Inter-Livres.


Reti, Ladislao, and Bern Dibner. 1969. Leonardo Da Vinci, technologist: three essays on some designs and projects of the Florentine master in adapting machinery and technology to the problems in art, industry and war. Norwalk, Connecticut: Burndy

Originally From Codice Atlantico di Leonardo da Vinci (C.A.,fol. 38LR)


Stradanus, (1580's by Stradanus., Straet, Jan van der, 1523-1605)

See web page above for picture.


Theophilus, John G. Hawthorne, and Cyril Stanley Smith. 1979. On divers arts: the foremost medieval treatise on painting, glassmaking, and metalwork. New York: Dover Publications.


Still working on proper form of documentation but I think I'm getting better. If you can't track where something came from, let me know.





Whats next on the great Machine
Happy Gerald


I am making a list of what I am writing about on the machine.  Since the next thing I build will be a grinder & polisher it will probably be next so that I can get some feedback before I start but I am open to focusing on what others might be most itche'n to see

Grinders and polishers
the wheel
the brake drum
the building and structure
the wheel axle
the bellows
the power hammer
the saw mill
the stamp
the main axle

Putting pictures in lj
Happy Gerald

I had a jgfsdjtmhcjfhafnamhgj!!! of a time getting pictures to go in LJ nice.  Anybody know how to get text to rap nice.  Much of what I have to show will be very visually driven.

Dogs in tread-wheels were period.
Happy Gerald

          Tread-wheels were one medieval alternative to water power. They were used in cranes almost exclusively with people as the power source due to the cognitive necessities involved in careful placement of loads.  In other situations thread-wheels seem to be an acceptable alternative where the more economical water power was not available.   People, horses, donkeys, goats, and dogs were all used but with the exception of people powered cranes, it is difficult to give precise documentation for more than one or two instances of a specific animal in a specific machine. 

          Dogs were used in tread-wheels during our medieval time period and this is clearly documented by Johannes Caius’s Treatise Of English Dogs.  First printed in 1576, the treatise was written for and presented to his friend, Conrad Gesner, between 1654 and 1565. Gesner died in 1565 therefore defining the date of its writing 11 years earlier than its first publishing. Caius discusses turnspit dogs and water dogs as follows:


“Of the dogge called Turnespete in Latine Veruuersator.


THere is comprehended, vnder the curres of the coursest kinde a certaine dogge in kytchen seruice excellent. For whē any meate is to bee roasted they go into a wheele which they turning rounde about with the waight of there bodies, so diligently looke to their businesse, that no drudge nor skullion can doe the feate more cunningly. Whom the popular sort herevpon call Turnespetes, being the last of all those which wee have first mencioned .” 1


“In Latine Aquarius in Englishe a water drawer.


And these be of the greater and the waighter sort drawing water out of wells and deepe pittes, by a wheele which they turne rounde about by the mouing of their burthenous bodies. This kind of dogge is called in like maner. ”2


 He also discusses many other working dogs with the same flair and dignity as dogs with more recognizable breed names.  One can not assume Caius to have been all inclusive. For example, he does not discuss the period use of dogs leading the blind as shown by Stradanus in the 1580's 3 or Agricola’s use of dogs with packsaddles to backpack bags for collecting ore up steep mountain slopes.4  Their may have other uses for dogs in a tread-wheel that he does not mention.

          Caius does not give us any pictures but a print of a kitchen (Fig 1) shows a detail of a turnspit dog by Thomas Rowlandson (1756-1827).5  Assuming this is depicting a pulley and cord drive, and not a chain one, it does not show any new technology over Caius, or Agricola.  Leonardo da Vinci discusses pulleys and cords as being quitter than tooth gear and lantern drum in the 1480’s6 so pulley systems are even a bit earlier.  Fig 1 is probably a good representation of what Caius was describing when he wrote of the “Turnespete dogge”.

Fig 1 Turnspit dog detail                Fig 2 French nailmakers dog powered forge

          Fig. 2. is too far out of our time period to be any support in the discussion of the medieval use of dogs, but it still is of value in a historical sense as it further supports the viability of the use of dogs for powering the bellows for a forge.7 Agricola describes several water, man, and animal powered bellows although not any tread-wheel versions.

          I am always on the lookout for more sources that document a wider range of machines and animals that were used with tread-wheels. There also was an external tread-wheel (Possibly developed by Leonardo da Vinci) which seems to be the forerunner of the railway or the tread power. (Railway powers also called tread powers had nothing to do with railroads.) They were a treadmill functioning very much like those you see at a fitness center except that the motion came from gravity and the walker not a motor moving the belt. They were tilted and dogs, sheep, or horses were put on them.  The treading surface belt turned by the weight of the beast and the roller turned or cranked a machine.  These machines were more compact than a tread-wheel so I would like to make one but I don’t think they are period.   In 1915 there were a dozen companies making them but by ww2 there were none.8  Fig 3 is a photo of one patented by Nicholas Potter in 1881.9  There are several excellent pictures in the webb sight listed in the bibliography below.  Agricola’s horse powered external tread-wheel Fif 4 is probably a forerunner that is getting close to this design.10. Of course any documentation that referred to dogs in tread-wheels, or any other medieval uses of dogs, would be especially precious.       

Fig 3 dog tread-power or railway-power      Fig 4 External tread-wheel




Caius, Johannes. 2005. Of English dogs: [the diversities, the names, the natures and the properties]. Warwickshire: Vintage Dog Books.


Footnotes:       1:Pg 34-35, 2: Pg 29


 (1580's by Stradanus., Straet, Jan van der, 1523-1605)


Footnotes: 3 See web page above for picture.


Agricola, Georg, Herbert Hoover, and Lou Henry Hoover. 1950. De re metallica. New York: Dover Publications.

Footnotes:   4: Pg 168      10: Pg 211


Thomas Rowlandson (1756-1827) Kitchen at Newcastle Emlyn. Courtesy of the British Museum

Picture found in Gastronomica Magazine.

Jeanne Schinto, “The Clockwork Roasting Jack, or How.....” Gastronomica. Winter 2004. Pages 33-39.

Footnotes:   5   Pg 34-37: Turnspit Dog


Reti, Ladislao, and Bern Dibner. 1969. Leonardo Da Vinci, technologist: three essays on some designs and projects of the Florentine master in adapting machinery and technology to the problems in art, industry and war. Norwalk, Connecticut: Burndy

Footnotes:      6: Pg 21

Bizet, Yves. 2000. Il était une fois-- les attelages à chien au début du XXe siècle. Collection nos terroirs, nos racines. Romorantin: Communication-presse-édition.

Footnotes:      7 Pg 150



Wendel, C. H. 1997. Encyclopedia of American farm implements & antiques. Iola, Wisc: Krause Publications.

Footnotes:      8  Pg 277-281

Footnotes:      9    dog power picture see web site above also follow links to more great pictures


Please forgive the Chicago style bibliography with fudged in footnotes. I need to learn how to do proper footnotes, but until then I think all the information is there and you can figure out hoe to track it from there.

I want to learn medieval German
Happy Gerald


I have always wanted to learn German. It is my family heritage. This was a mild want until a friend offered to give me pictures of a 15th C of a German brewing text. So the straw that broke the camels back in this case was being carried by an elephant. Some local folks are offering some books and a tape but I haven't got them yet since I just asked. I don't speak any at all although my grandmother and her sisters did. I really am serious about this. The real focus would be on learning to read and translate period text(s). I would like to do this learning efficiently so I am asking for advise. My friend has already sent me a CD of a book on metallurgy and I can tell by the woodcuts it parallels some translated sources I already have but brewing is what I got my laurel in. Lately, as in the last couple of years, the stuff coming my way has been mostly 1500's German and some high quality information at that. It is really ringing a bell and so after 30 years in the SCA being a floating century hopping persona I think I have found a place to settle.


Gerald Goodwine

Happy Gerald


Dear friends


I joined LJ as a way to present information about my machine and network on it and other projects I am working on. I am a slow reader, probably dyslexic, and computers make my eyes burn after a while. If I have not friended you back, please don't think I am not interested in you or what you have to say. Please understand that it is most likely my meager attempts to manage what would be overwhelming amounts of reading. I am pleased and somewhat surprised that I already have been friended by you all. Thank You!

Happy Gerald

If anyone comes across an actual medieval recipe for making rennet of small ruminant stomachs I will do it.  I know of others who would also be interested.  Until then my time will be spent elsewhere.

Gerald Goodwine

Tags: ,

Wanted: a winemaker to serve as a lab tech.
Happy Gerald

(Here is a beautiful example how interwoven medieval industrial material culture was.) But to gain command and understanding of these processes we have some work to do.

The Greeks, and, I seem to recall one case, a medieval European used salt in wine. 

A simple test with salt I have done suggest that in wine-making it can counter some of the undesirable effects of oxidation but may have some undesirable effects of its own. 

Read more...Collapse )

Anyone up to the challenge?

Hello from Master Gerald Goodwine
Happy Gerald

I am new to Live Journal and am not that great with computers but I am told that this would be a good venue for me to talk about my machine. “The Great Machine”, as some people have started calling it is a dog powered tread-wheel intended to be the power source for a number of period machines based on late 15th and 16th C. technology. The tread-wheel is now operational and I will shortly be posting some research on medieval grinding and buffing wheels- the first machines I intend to power with it. It is a huge project and already there have been many surprises, successes, failures, and discoveries. I hope to share these experiences with others interested in historical technology.


Log in