Difficulty minimizing tooling marks from machine

[Hemskey]

Hello fellow leather workers -

I recently purchased a techies 4800 pro, and I'm having a lot of difficulty on removing some of the tooling marks in the leather along the stitches. I have been wanting to get better with the machine for sewing basics (back-stitching, straight lines, curves, etc); however, I'm very confused on how I can minimize these marks.

On the top side, I'm getting marks from the walking foot - which at this point I've accepted. I'm not sure how I could do anything further - Techsew support had me remove the walking foot rod and spring that kept tension which has had some undesirable effects, but I digress.

On the bottom side, I'm getting a lot of bulge on the leather around the needle pushing through. I was told to try a smaller needle, so I've used the smallest needle for my current thread (size 20 135x16 Schmetz Diamond Tip). I was using a size 24, and the bulge isn't that much smaller in my opinion. I'm also getting marks from what I assume is the bottom walking foot, the lines are straight and seem to be part of the rectangular piece. I've sanded that piece along the edges to try bring down some of the scratches but I'm still getting this.

Couple of questions, first one being a reality check. Am I having unfair expectations of my machine to leave less marks? If not:

1. How can I remove some of these tooling marks on the bottom side?
2. How can I minimize the bulge around the needle holes/stitch lines?
3. Is it possible to bring down more of the tooling marks on the top side?

Images of the stitches:

1. Top side of the stitch: https://drive.google.com/file/d/1KoVdf-yPiMw0bxs0tlnH96liec4NLDYr/view?usp=sharing
2. Bottom side of the stitch: https://drive.google.com/file/d/13rxiYevsDJ3j742raD8zXJqkQkxO9AYI/view?usp=sharing
3. Spring cut off from the presser foot spring (advised by techsew support): https://drive.google.com/file/d/1jq1K-toKJ7K8qOnzNCWRqPOtOxDk3SCi/view?usp=sharing
4. Rod and spring removed from top walking foot (advised by techsew support): https://drive.google.com/file/d/1XDzDcMOz6m17LSCabhr6ZEg5GgGMfUSK/view?usp=sharing

If there's any additional info, I likely have it. I'm an open book and just want to become much better with this machine. I've ran back to techsew support but I can't seem to get anything further after a fair amount of back and forth on this. As with the internet, if I'm being unfair in my expectations then I'm sure I'll be told, but I welcome that. On the flip side, I look at other machine stitched leather work around my area, and I feel there is room for improvement.

Leather is harness from W&C, 8oz. I've used pull-up 4oz leather with similar effect. Harness does mark much easier so I certainly acknowledge that part of all of this. Okay, I'll stop writing. Please share some knowledge and guidance!

[kgg]

32 minutes ago, Hemskey said:

If there's any additional info

First off the Techsew is sort of a Juki LS - 1341 / 1342 clone so the Juki installation / engineering manuals would be a good resource to have. Did you get any manuals from Techsew with the machine????

As far as marking goes the first place I would go is adjusting the height of the feed dog. If it is to high it will mark the underside and cause the top presser feet to be pushed in to the top side of the leather as well as contribute to the needle hole bulging. The bulging looks to me like the size of the hole in the middle presser foot. The manual will explain how to adjust the height of the feed dog.

As far as the correct size of needle it will depend on what thread size you are using. The size 20 needle is typically good for V92 in thinner leather while the #24 would good for V207 in thinner or V138 thread in thicker stuff.

Here is a good cross reference of needle size to thread size: https://www.tolindsewmach.com/thread-chart.html

kgg

Edited February 26 by kgg

[Hags]

I usually wet and hammer the stitch line. This closes the holes a bit, smooths the stitches, and removes a lot of the machine marks. 

[Hemskey]

@kgg - I definitely have some manuals, and I've been a frequent visitor of that and the YT channel they have. I'll try adjusting the feed dog to be lower and see what kind of results that will have on the stitch line. I appreciate the tips - I'm excited to give them a try! I'll keep the needle/thread guide handy.

@Hags - I'll hammer the stitch line just to see what the outcome would be with the way things are now. I intended to hammer stitch lines but the marks have certainly distracted me from that. Good reminder and I'll give that a try. I'll do that after doing @kgg's recommendation, too. PS: A great friend of mine is from your area, I hope you can enjoy some Oak Table for me

[TomE]

Great suggestions from @kgg and @Hags.  I tap the back side of the stitching with a polished hammer on a smooth stone.  Some folks use an overstitch wheel to smooth out the stitching.  Also check the type of cutting point on your needle.  I think the "S" type cutting points produce less blow out (backside bulges) than the "D" type triangular needles that are good for stiff leather. Here's a guide  https://cdn.shopify.com/s/files/1/0579/8857/9507/files/Cutting-Points-schmetz_db_schneidspitzen_6s_20190510_en.pdf?v=1643753018

[Hemskey]

@TomE I can certainly order the different needle types - I was under guidance that diamond was the way to go from Support so I ordered all the sizes in that type. I'll do the same with the S type if these other suggestions don't help out at all.