Hi, Bill:

THanks for your sharing, appreciate it.?

hi, David:
thanks for your reply, how about 45 and 60 degrees? or just only 18 you use mostly??

Henry

The 30° and 60° references as standards are usually found when operating a lathe.

The tool rest slides on a compound that rotates and has graduations in degrees with 0° being parallel with the axis, 90° is therefore perpendicular to the axis. The tool rest advance is graduated in thousandths of an inch, either in reference to the diameter of the part being machined or in reference to the radius of the part being machined, depending on the brand and model of the lathe. Either way when changing the Depth of Cut (DOC) one can use either the cross slide for direct measurement or one can use the tool post advance. If the tool post is set to 60° and the tool rest is advanced 1 graduation of the dial the change in DOC is 1/2 the reading on the dial. When making facing cuts (reducing the length of the workpiece) setting the compound to 30° will advance the tool into the work 1/2 the reading on the dial.?

The math behind this and other tricky lathe compound settings are far beyond the scope of this thread so please do not drag this on here, there are other forums for that. One in particular you may find interesting (if you are not already a member): /g/atlas-craftsman

Raymond

Actually 18 degs’ , Just needed a little filing to clean up and square

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These little guys are cut at 40 degrees.
(attached)

Other Bill

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Depends on what you are doing.
I used to make a lot of parts for processing equipment, which required various angles, including 30 & 60 degree.
Most common is 45 degree, for miter cuts on square corners, but some things require different angles.

Attached is an example: Feeder spouts, cut at a 30 degree angle, made of 304L. I made a cutting fixture just for such angles.
Building any exhaust system parts? 30 degree is common for outlet tips. I've built some of those too.

Other Bill

Hi Guys,

Welcome to share with me the comments of above subject.??Why people need? 60 , 30 degrees for cutting ?? In what condition, what material, what applications we need these angles ???
Any comments will be highly appreciated.?
Thanks.

Hi Guys,

Welcome to share with me the comments of above subject.??Why people need? 60 , 30 degrees for cutting ?? In what condition, what material, what applications we need these angles ???
Any comments will be highly appreciated.?
Thanks.

Thanks.

I’m pretty much a hack when it comes to tools. ? These are things I borrowed from others or figured out on my own to improve the saw. ? It works great now. ?I just need to use it.

Quin (blondihacks) is an amazing machinist and teacher. ? I think she’s a software engineer too. ? She’s definitely ‘smarter than the average bear.’

I enjoy her YouTube channel too. ?My work is barbaric relative to her stuff.

Dave:

Your mods are amazing.
I think you have surpassed the original manufacturer's content and most of that saw is now 'yours.

I do not have a problem with loose pivot bushings, but you are right that any little bit gets magnified by the length of the head (and of course the flex in the frame doesn't help).? I think these deficiencies become tolerable because there is not much side force when cutting.

I recently found a YouTube video by 'Blondihacks' where she is really pushing the limits of a 4 x 6.
The result that she gets is quite good.? Apparently her saw cuts pretty square (looks like it is probably a JET).
I think you guys would enjoy it...

The relevant part is from 14:00 to 17:00 minutes if you want to jump right to the 4x6 section:


-Tom

A few comments:

* ?I drilled, tapped, and brass plugged a 1/8” NPT in my gearbox body and filled the box with the saw in the vertical position. ? I couldn’t tilt the saw due to my new stand. ? I really prefer the fill plug.

* I found that sawing wood didn’t work as well as sawing 1 1/2” round steel. ? Most of my squareness inconsistencies was due to the slop in the pivot bushings. ? The bushings were still reasonably round, but were grossly oversized. ? I turned a new pivot shaft and got it just right with very acceptable clearance. ? This is critical for getting reproducible cutting squareness.

* ?I actually filed my table so it was parallel to my pivot shaft. ? I did this because I got the pivot shaft so well sized.

* ?The saw frame is not very stiff. ? I replaced the blade hand tightener with a stud and a thrust washer and nut. ? I tighten the blade until it runs true and then give it 1 1/2 turns to tension the blade. ? ?This needs to be done before fiddling around with trying to square the cut. ? This should reproducibly distort the saw frame to the same position.

?I did all sorts of modifications to my saw. ? I bought my saw for $20 and this is the only reason why I haven’t spent more money than what I would have spent on a good saw that worked right out of the box. ? I have my mods shown in the photos section. ?

I’m really enjoying seeing comments from the’old guard’ and some new members!?

Dave

If I click on one of these 'broken' images in my original message (for instance the bizzare name: xdp-IMG20231224115318_small.jpg-hj2xcM), I can download it, change the name to something like 'testsmall.jpg' and the image is just fine.

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try to email the pic's to yerself & see ifin it wigs out

animal

The images I tried to submit were very small (abut 300 x 400 pixels, each less than 30K).

It is very odd because when composing the message, the images appeared in-line with the text just fine.
But, when I submitted the post, they got messed up as you saw.

Subsequently, I tried composing a test message with the same images, and instead of submitting it, I did a 'preview'.? Again the images got messed up.

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Ya could try puttin them in the photos section of the group ..

animal

"My original file names were not like that.? They were just plain jpg.? When I uploaded them into my message, they looked fine.? It is only when I posted (or previewed them) that they broke.

Interesting!? I wonder if perhaps they exceeded some size limitation?? I've dragged & dropped images with no problems, but I usually use GIMP to scale them down to about 800 x 680.

Perhaps our Great Moderator(s) could weigh in on this.

Mark
?

Tom,

It might be the strange file extender for all your images.? The forum S/W probably didn't know what to do with them.? Try removing all the text after ".jpg".

Mark

Not sure what happened to my pictures in the previous post.
They were just small .jpg files, and I had no trouble with inline pictures in earlier posts...
They seem to be broken.

-Tom

Just a follow-up to describe my experience with the head alignment process...
I used bi-directional cuts with a S4S 1"x5" pine board to evaluate the pivot tilt.

My starting point with no shims yielded a thickness difference between the top and bottom of the cutoffs (double sided) to be around 0.136".? This implies that a pivot offset of about 0.068" would be required (half of the measured difference).

Here is part of the aftermath




Next, by using different shims between the table and the board, I found that a 0.082" shim provided a 'straight' vertical cut.? As recommended, I did multiple cuts with each setting in order to be able to average the measurement.? Since the distance from one edge of the table to the other is about 6.5" and the length between the pivot supports is more like 5", I decided that I needed to scale the 0.082" accordingly.? So I proceeded to make a new pivot shaft that lowered one end by 0.082 * 5" / 6.5" ~= 0.065".? Note that this is pretty close to the initial estimate based on un-shimmed cutoff measurements.

Here is the new shaft:


After installing this shaft, I did some more test cuts.? Although much better, I felt like I needed to go a little further.? The difference between top and bottom of the cutoffs went from 0.136" to 0.022".? Based on this, I re-machined the shaft to increase the offset from 0.065" to 0.080".? Unfortunately, this went too far.? My difference between top and bottom changed from 0.022" to -0.022".? I guess I really need to split the difference with the offset.? I should have declared victory with the first offset...? It was really good enough.

At this point, I'm going to just leave it alone and see what happens with metal cuts in real material.? It is clear that one cannot strive for perfection out of these machines and I think I have reached the point of diminishing returns.? On to other upgrades like a better vertical table and adding the longer vise jaws...

Some lessons learned:

• I did change the gearbox oil (used the Redline).? For my gearbox, it seemed like 200 ml was a good amount.? I used John's suggestion of propping the front legs of the saw up by 3 1/2" (using a 2 x 4 with the saw in the horizontal position.? 200 ml rose to a level where it was just about to spill over the lower edge of the open gearbox.
• I was disappointed in the wood cutoff measurement technique.? I felt like the behavior of the wood may not be representative of how the machine will cut metal.? Perhaps averaging multiple cuts helped but it seemed like the grain of the wood was affecting the path of the blade in a non-random way.? I did ease the blade through the wood by gently lowering the head over the course of maybe 15 seconds.? I used a pine board which has a fairly loose grain.? Occasionally there was a knot and I could see that the knot definitely had an effect so I would avoid them.? All in all, I did not feel like I got a reliable reading even with some averaging.
• In lowering the blade side of the pivot (by .065" to 0.08") it was clear that there was not enough play in the opposing pivot support.? It was not possible to lower it even this 'small' amount without either flexing the pivot shaft or placing undue stress on the opposing pivot.? So, I wound up using a reamer to widen the opposing pivot support enabling the proper amount of shift on the blade side of the shaft
• I drilled and tapped the blade side pivot block and used a setscrew to tighten the new shaft.? And of course removed the original bolt that secured the shaft to the frame because that is now the new pivot point.
• Once the blade side was lowered, the new position caused the plastic blade guard to touch before turning off the machine.? It still works but the final 1/8" of the cut is flexing the plastic guard and affecting the down pressure of the saw.? I still have to work on a better solution for this.
• I am not confident that it is 'right' based on the behavior I saw with the wood cutting, but it is certainly good enough to stop tinkering for now.? If it turns out that I overshot the desired offset, then I will add a little metal tape under the modified shaft to bring it up a hair rather than make another shaft.
• During this process, I captured a lot of details in a spreadsheet to keep track of test conditions and results.? I found it useful to avoid getting mixed up as I went through the process.
• The head is heavy and awkward and I struggled to get the pivot shaft in and out while trying to balance / position the head.? It has to be positioned just right in order to get the shaft in and out without getting stuck.? I hesitated to use a drift because I did not want to force it, risking damage to the pivot blocks.? Two people would have made this easier.

Thanks again for all the insight gained through the amazing people in this forum !!

-Tom