TomE

I am not familiar with your machine but it looks like the knots are showing on top when the stitches become irregular. Would help to describe the weight of leather and needle and thread you're using. Changing the needle can affect the top tension. I don't understand the problem with your presser feet. If they have teeth then grinding and polishing the feet is an option.

Although @bruce johnson didn't say it, he sells high quality leather tools that are sharp and ready for use. Check out Bruce Johnson Leather on the web and on Facebook.

Thank you @bruce johnson, @chuck123wapati, and @AlZilla for your thoughtful replies. You all raise interesting points that will influence my experiments with leather this winter. Hope to spend more time in the leather shop once I finish the fall/warm weather chores - spreading manure, replacing broken fence posts, and weaning the foals. Thought I might turn this hobby into a business someday but my wife's business uses up most of my time. Maybe there will be a brief span when I'm too old to mess with horses but young enough to mess with leather.

I don't know of a good way to skive with a Class 14. It is best used for thinning larger pieces of leather than can be done with a manual pull-type splitter. It is also easier to do long splits on the Class 14. I still use my Tandy Pro splitter for lap skives on the ends of straps.

Would a bumping dolly be heavy enough to replace the anvil? One person holds the dolly and saddle and another person sets the rivet. They come in a variety of shapes for auto body work. Eastwood Co. sells quality tools https://www.eastwood.com/fairmount-double-ended-round-dolly.html

Nice design. I'm interested in seeing how you construct the slings. The only thing I know about duck hunting is that it's cold.

Looks like a comprehensive course and teaching is a great way to extend the teacher's skills and understanding of their art. For folks who don't have experience with the listed techniques/tools it might be helpful to provide a narrative overview of the skill areas covered by the course - construction methods, project design, tool maintenance, finishes, etc - or some learning objectives for each lesson. I taught medical and graduate students for 25 years and was asked late in my career to provide learning objectives for each lecture. That exercise made me think more critically about how the topics fit together, how to prioritize them, and what the takeaways were for each lecture. The learning objectives weren't " know this and that" but instead they were "be able to explain this and do that."

Bridle and harness leathers stuffed with waxes and oils will absorb neatsfoot oil without a problem. I’ll guess the leather was sealed with acrylic or similar finish. Cracking of the grain may well be due to low quality tannage. Might try burnishing the edges as another test of quality veg tanned leather. Maybe @RockyAussie or someone else can suggest a good leather supplier in your part of the world.

Beautiful folk art! Thinking about a summer day (although I'm happy that fall has arrived).

Y-knot Lace has a good selection of kangaroo lace that could be braided to make a drawstring. I've been pleased using it for laced reins. https://y-knotlace.com/

Looking forward to hearing about your experiences with the raised leather. Always looking for new ideas and improvements.

I've had the impression that the grain layer of veg tanned leather contributes more to overall strength than an equal thickness of the flesh layer. This has been suggested as a reason to not use a stitch groover (removes the strongest part of the leather), and why splits are stretchy and weak compared to full grain leather. Well this paper from 1926 says the opposite. On per thickness or per cross sectional area basis the flesh side is stronger than the grain. For example, the grain side of a split that retains 70% of original thickness has half the strength of the unsplit leather. The flesh side split to 40% of original thickness retains half of the strength. Maybe not a big deal but it indicates that the grain doesn't have an outsized contribution to strength, at least not for these authors' cow hides. The sum of the strengths of grain and flesh splits is always less than the strength of the unsplit leather- that much I can understand. Does this comparison of grain and flesh agree with your thinking? I am particularly interested in the strength/stretchiness of straps. Seems it would be stronger to line a thick strap with a thin liner instead of using 2 straps of equal thickness that add up to the same overall thickness. Wilson and Kern - 1926 - Effect of Splitting on the Tensile Strength of Lea.pdf

I'll bet the horse will turn up if you fill the bags with feed. Did you include hardware to tie the bags on your saddle?

Looking good! I like the 3mm stitch spacing and it looks like you're using an awl.

The nice thing about the narrow feet is you can turn sharp corners without coming off the edge. With the in-line feet I back out of square corners so the rear foot has a place to land.

A couple of articles on tanning chemistry and several on currying - fats and oils. The files are too large to upload here, so here is a link to my Dropbox folder containing the files. https://www.dropbox.com/scl/fo/1unoj2zvcdb9xjo65u993/h?rlkey=4rx8dv5fz2obchca3n6k27qyh&dl=0

I have read that the stepwise increase in tannin concentration during the tanning process produces a more uniform matrix of cross linked collagen fibers. If the concentration is too high at the beginning there’s a lot of cross linking near the surface, creating a barrier to penetration deeper in the leather. It is my understanding that tannin solutions are used for multiple runs of tanning, starting the process with used solutions that are depleted in tannin concentration and working towards newer solutions with a higher tannin concentration. In the end some tannin molecules are tightly bound to collagen (hydrogen bonds and salt bridges) and a portion of the tannins can be extracted through back soaking. If you’re interested I can post some articles describing these aspects of the chemistry.

I like the appearance of the S point needle stitching and use it mostly for 15-30 oz bridle leather. The TRI needle creates a more noticeable hole but is good for hard leather with little tension adjustment. The Schmetz website is my go-to for needle information. https://www.schmetz.com/en/industrial-needles/needle-compass/cutting-points/

The inline feet from Toledo Industrial Machine work great on my Class 4. So does the narrow foot set from Hennigen Precision Engineering.

My brother made a rounding block for me out of pine and I gave it a light coat of beeswax. This was a prototype before he makes one out of hardwood, but it has been working fine for 18 months. The only commercial rounding block that I found is sold by Abbey England. The brass ball sounds like a good fit. I use a bone folder an a large pear shader for 5/8" straps. The trick about sewing a swell with a machine is there's no flat surface for the pressor foot and the strap slips sideways under pressure. Will be very interested in how you do this. For raised leather with a flat filler strip an inline foot can be used on the narrow margin, but to sew really close to the raised element I run an inside foot on top of the filler strip.

I buy stamped stainless bridle buckles and stud hooks from Weaver, and most of my heavy brass halter hardware from Batz Corp. Abbey England has unique, high quality hardware for English tack but shipping is REALLY expensive, so I usually treat myself to a tool to justify the shipping cost.

@jcuk covered it well with the links. I'd only add that the first 2 video links are what I call a "swell" -2 straps with skived edges formed in a rounding block. The 3rd link is what I call "raised leather" - a split strap with a filler inserted. Whatever terminology you prefer they are different techniques. For swells I use a Japanese style knife or a head knife for most of the skiving and do a bit of leveling up with a French edger. I case the top strap after skiving and shape it in a rounding block, check its fit to the backer strap, then let it dry a few hours before gluing and assembling the 2 straps. I keep the backer strap dry and shape the curved front around it. I haven't figured out how to sew swells on a machine so I hand sew them. For raised leather I am splitting ~10 oz leather to ~ 3 oz of grain side and the rest as flesh side, or I split another strap for the backer so both sides have grain showing. The backer strap serves as a stiff platform to shape the grain side around a filler strip. I use a ~5 oz filler strip for a 10 oz split strap. The edges are trimmed after gluing and assembly, so I typically start with a strap that is ~3/8" wider than the desired finished width. You'll need a larger margin if sewing with a machine. An in-line or narrow pressor foot set will help. I have a bucket full of practice straps that are my raised leather graveyard. By playing around with thicknesses and widths you can create different looks.

I thought the main reason to use tallow instead of lard is that tallow resists oxidation/going rancid.

Might try maintaining it like horse tack. Cleaning with saddle soap and water. Occasional oiling as needed with neatsfoot oil. Conditioning with a waxy conditioner like Fiebings Aussie or Black Rock Leather-N-Rich to repel water. English tack is not sealed with an acrylic top coat. Depend on regular cleaning, and conditioning with fats and oils to keep it supple and prevent dry rot. Another way to go is silicon oils for water proofing. Fiebings Saddle Oil (I use it on my work boots) or Golden Mink Oil.

While we're on the subject of fats and oils... Newbury - 1940 - Oils, fats and waxes in the leather industry.pdf Blockey - The Application of Oils and Greases to Leather.pdf