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Hi
Gang:
Send me
your dumb questions. I have all the dumb answers!
Ha Ha.
Sincerely,
Carl.
On 3/26/2023 10:33 PM, OldToolmaker via
groups.io wrote:
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Show quoted text
There is no such thing as a dumb question! Never was and never
will be!
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Show quoted text
El lun., 27 de marzo de 2023 7:58, Carl < carl.blum@...> escribi¨®:
Hi
Gang:
Send me
your dumb questions. I have all the dumb answers!
Ha Ha.
Sincerely,
Carl.
On 3/26/2023 10:33 PM, OldToolmaker via
wrote:
There is no such thing as a dumb question! Never was and never
will be!
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Dang - and I thought I had all the dumb answers tied up!
DW
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In this vein - and I realise this is a Unimat group - anyone know the colour code (pantone, rustoleum etc) for the yellow Compact 5?
Hi
Gang:
Send me
your dumb questions. I have all the dumb answers!
Ha Ha.
Sincerely,
Carl.
On 3/26/2023 10:33 PM, OldToolmaker via
wrote:
There is no such thing as a dumb question! Never was and never
will be!
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Only having seen the Compact 5 in photos, I may be wrong but the shade looks the same as Old Caterpillar Yellow. If anyone agrees, it¡¯s? Rustoleum #209715
DW
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Thanks Dave. As good a quess as any.
On Thu, Mar 30, 2023, 8:13 PM Dave W < fahrwud@...> wrote: Only having seen the Compact 5 in photos, I may be wrong but the shade looks the same as Old Caterpillar Yellow. If anyone agrees, it¡¯s?Rustoleum #209715
DW
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I have one! ?
I¡¯m about to use the top slide (the adjustable one that can be used to cut tapers) on my U3 for the first time. The tool post has three fixing bolts, but due to their arrangement it looks as though only one bolt could be used to secure a normal straight cutter, compared to using two bolts of the standard tool post.
Is this correct? Am I missing something? I¡¯m new to lathe work so probably have plenty of dumb questions left :-)
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Yes and I don't like it but it works go easy with your cuts
On Sat, 8 July 2023, 3:59 pm Peter Brooks, < peter@...> wrote: I have one! ?
I¡¯m about to use the top slide (the adjustable one that can be used to cut tapers) on my U3 for the first time. The tool post has three fixing bolts, but due to their arrangement it looks as though only one bolt could be used to secure a normal straight cutter, compared to using two bolts of the standard tool post.
Is this correct? Am I missing something? I¡¯m new to lathe work so probably have plenty of dumb questions left :-)
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I have a dumb question - why are there flat, cup and cone termination varieties of grub screw, when bolts only (as far as I¡¯m aware) come in one style?
I¡¯m guessing they have a specific purpose¡
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Kevin Groenke @ PersonMakeObject
I was thinking of writing an answer but just did a copy/paste from Wikipedia instead. Also, many bolts do have different end shapes.
"Set screws appear with a variety of tip (point) types. The different shaped tips have different properties that engineers can utilize. If an engineer were to use a detent to ensure proper nesting of the screw, they might choose to use a cone point type of screw. One might often need to use a flat point when the screw must press perfectly flat against a surface. The most common type is the cup point. This type works well because the surface is rounded so that a small surface area is in contact, but it does not have extremely high stress at one point like that of a cone point. Durability studies show that the cup point offers superior resistance to wear while maintaining a strong grip. Knurled cup points offer the added advantage of a locking action (similar to that of a serrated lock washer) that prevents the screws from working loose in high-vibration applications."
On Tue, Aug 29, 2023, 1:57 PM Peter Brooks < peter@...> wrote: I have a dumb question - why are there flat, cup and cone termination varieties of grub screw, when bolts only (as far as I¡¯m aware) come in one style?
I¡¯m guessing they have a specific purpose¡
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Hello
Peter:
You are
right, bolts usually only have the straight end, but there are
self-tapping ends.
But the
Point is the "working" end of a set screw, and each Point has
a special purpose.
Flat
and Oval points are mostly for clamping and not damaging the
shaft.
Cup and
Cone points are for more robust clamping where scoring the
shaft is acceptable.
Dog and
Half Dog points (also called
extended point)? often seat in slots in shafts allowing a
sliding fit.
Soft-Tip
points avoid damaging the shaft and can be brass or plastic.
There
are also Hollow-Lock set screws for locking and adjusting a
second set screw.
Check
for a large assortment.
Carl.
On 8/29/2023 2:57 PM, Peter Brooks
wrote:
toggle quoted message
Show quoted text
I have a dumb question - why are there flat, cup and cone
termination varieties of grub screw, when bolts only (as far as
I¡¯m aware) come in one style?
I¡¯m guessing they have a specific purpose¡
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If you look carefully, many bolts are not actually flat on the end.? At times I have had to machine the end of a screw flat to not have marring.
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Kevin Groenke @ PersonMakeObject
Also, the reason set (grub) screws have many end varieties is because that is a "working" portion of the design. On typical bolts and applicatiin, the primary "working" portion of the design is the head and shoulder which, of course, there are almost countless varieties of.
On Tue, Aug 29, 2023, 1:57 PM Peter Brooks < peter@...> wrote: I have a dumb question - why are there flat, cup and cone termination varieties of grub screw, when bolts only (as far as I¡¯m aware) come in one style?
I¡¯m guessing they have a specific purpose¡
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Yes the typical smaller screws are cold formed. The end of the screw shows what happens when a formed thread is not supported. Those smaller screws are squished between 2 plates with slanted grooves. That is what forms the threads. When the cylindrical shank is squished some of the material deforms out of the end of the screws. If the screw has a squished looking end it was cold formed. If it is perfectly flat with a chamfer then it is machined out of bar stock. Usually over 1¡± are machined.?
Under a 1/4¡± are made on high speed machines, 1/4-7/8¡± are on larger former machines and 1¡± and over are usually machined. That is why pricing changes quite drastically around those sizes.?
?
If you look carefully, many bolts are not actually flat on the end.? At times I have had to machine the end of a screw flat to not have marring.
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I have another newbie question - boring bars.? I have recently got (used) some 'proper' boring bars. What a difference compared to the carbide insert variety I was trying to use before! 1) They have round shanks with a flat. I'm assuming they fit into a holder with a circular hole, secured with a grub screw (a bit like UnimatMatt's 'Swiss Cheese' holder). The shank diameters however are (mm) 5.2, 6.6, 8.2 and 8.3. which equates roughly to 7/32,? 17/64, and 21/64 in Imperial. What's going on? These drill sizes are no doubt available but they can't be particularly common... 2) If the boring bars fit into a holder with a hole and a grub screw (from the top) to secure then they will be cutting (internally) on the opposite side of the work to normal cutting. This is fine (as the cutting action is the same as normal external cutting) but I just wonder if it is the intended method of operation. Thanks!
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This will give you a pretty good idea of how they're used. Note, also, that they can go in 90 degrees from the boring bar that's mounted in the photo, for cutting really large holes. It will take a LONG while to do something like that. They will also chatter like mad given half a chance. Folks who do work like that regularly have special tooling for that purpose.?
They can be used in a lathe or a milling machine, depending on what shank they are mounted on. Some come with an assortment of shanks, and some come alone, and you buy the shanks you want. That's way cheaper than buying a boring head with a fixed shank for each type and size. I've got machines that use MT4, MT3, MT2, R8, and a specialty bore on the SB Heavy 10L that is about an MT4.5 or so.?
For a Unimat, the Swiss-cheese holder that you mentioned is going to be fine, but it, too, will allow chatter easily. But if you need a specific size hole, and don't have appropriate bits AND REAMERS, you'll need an assortment of boring bars. Drill bits do not drill accurate holes. The practice, when you need a perfectly sized hole, is to drill 1/64" or so undersized, and then ream. Imperial reamers come in the standard fractional sizes, and also over/under reamer sets, with pairs, one .001" over sized, and one .001" undersized., I've got a couple sets of imports, and still have nearly $200 in them. Plus assorted reamers that don't fit in the sets. Bear in mind, of course, that I have CDO, and aspirations. ;)
Bill in OKC
William R. Meyers, MSgt, USAF(Ret.)
Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY!
Expect in one hand, expectorate in the other. See which one gets full first.
On Thursday, September 21, 2023 at 01:26:38 PM CDT, Peter Brooks <peter@...> wrote:
I have another newbie question - boring bars.? I have recently got (used) some 'proper' boring bars. What a difference compared to the carbide insert variety I was trying to use before! 1) They have round shanks with a flat. I'm assuming they fit into a holder with a circular hole, secured with a grub screw (a bit like UnimatMatt's 'Swiss Cheese' holder). The shank diameters however are (mm) 5.2, 6.6, 8.2 and 8.3. which equates roughly to 7/32,? 17/64, and 21/64 in Imperial. What's going on? These drill sizes are no doubt available but they can't be particularly common... 2) If the boring bars fit into a holder with a hole and a grub screw (from the top) to secure then they will be cutting (internally) on the opposite side of the work to normal cutting. This is fine (as the cutting action is the same as normal external cutting) but I just wonder if it is the intended method of operation. Thanks!
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Number 2) is not clear to me. Seems I need more information, as your comment about where the cutting will be depends on the shape of the boring bar.
Martin P.
On Thursday, September 21, 2023 at 02:26:37 PM EDT, Peter Brooks <peter@...> wrote:
2) If the boring bars fit into a holder with a hole and a grub screw (from the top) to secure then they will be cutting (internally) on the opposite side of the work to normal cutting. This is fine (as the cutting action is the same as normal external cutting) but I just wonder if it is the intended method of operation.
Thanks!
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Thanks Bill and Martin. ?I¡¯ll post a photo of the bars tomorrow - it¡¯s just gone 22:00 here in the UK.
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A common holder for round tools is a normal tool holder, but with a vee groove in the bottom face, and clamping screws above. Rigidity is the problem - you really want the boring bar to be as short as possible for the job you're doing. Clamping screws as near the sharp end a possible will also reduce chatter. With a vee groove and height adjustment the exact size of the boring bar doesn't matter. If you use a block with a hole in it I would use 5.5, 7 and 8.5 mm for the sizes you have. You need a little clearance, and once you have clearance it doesn't matter much how much. Unless you hold the bar in a collet it will not be a solid mounting.
A thought - you could grind the other end of the boring bar into a D bit to make an accurate hole in a holder, then it wouldn't matter what the nominal size is. But whatever you do I think you will always need a height adjustment. It's not practical to shim under a round bar.
In use the tool point will be facing towards you, whereas all other lathe tools (that I know of) face away from you. That also means that it is doubly difficult to see how the cut is going - it is in a hole and facing away from you. However, on these little lathes you could easily operate it from the tailstock end and have a better view of the cut.
As for precision sizing of holes, yes, drills cut oversize. By how much depends on speeds, feeds and the material being cut. (Actually in some plastics drill cut undersize.) But if you use a smaller drill first, then open it up with a slightly bigger one, it acts more like a reamer and cuts to the actual size of the drill. Use a slower speed than for normal drilling. I needed to drill some accurate 1 mm holes in hard brass.to take a nominal 1 mm shaft, actually very slightly undersize. I drilled it 0.9 and finished off with a 1 mm drill, which actually measured 0.99 mm. I finished up with a hole that was a squeaky fit on a bit of 1 mm silver steel (drill rod) that measured 0.995 mm. After that the customer used a hand reamer to get a finished size that suited his motor shafts.
How much undersize drills are, compared to the nominal, varies. I had to make careful selections with a micrometer to get the best one for the job. The oversize cutting is caused by the drill point, which does not actually cut, so it just pushes the metal out of the way. This causes the drill to wander a little. How much depends on exactly how the drill is ground. A thin point may break off in tough materials. A thick (strong) point will need more force and will be less accurate. When opening up a hole the drill point is in fresh air so has no effect.
If you must bore out holes try to drill them as large as possible first. Consider using a milling cutter in a Dremel, or other motor, mounted on the toolpost. The options on these little lathes are limited, but with a bit of cunning a lot can be done.
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Carl
Dave W
Tool247
Bill in OKC too