Hawk BM26 Review Update - by Iggy

[hotshot]

I did find out what I was doing wrong, and it was "simple".  I had the rear tension lever engaged, but for some reason, I was thinking the end of the knob would face the back, not the front.  man did that make a huge difference in vibration, and in having the knob not rotate.

Here is my BM26 running full out, passing the nickel test.  I think any more vibration, and it would not have passed.  But, having that much moving mass, and squelching vibration to this degree, it's pretty impressive.  I did have to place the nickel towards the center of table. 

 

Edited July 22, 2017 by hotshot

[stoney]

I for one am really enjoying this type of thread for the frank discussion that has resulted.   I used to get pretty tired of some of the defending to the max of any scroll saw the was being discussed or reviewed just because that happened to be the brand that was purchased.   I have always appreciated an unbiased, honest, evaluation of any product I might be considering.   Thanks to all that have contributed to this discussion.     

[Mark SW]

I also appreciate the honest and sometimes difficult responses.

The BEST is that Scott from Bushton is taking and active and honest  approach for which I truly admire.

Mark

[tonylumps]

Does anyone own a new BM 20 or 26 on SSV.that has been using it long enough for a review.According to Bushton they are really selling a lot of them. Is it mostly production type of work.I know we will get a good review from Iggy But is there anyone else using the new Models.

[kmmcrafts]

11 hours ago, hotshot said:

I did find out what I was doing wrong, and it was "simple".  I had the rear tension lever engaged, but for some reason, I was thinking the end of the knob would face the back, not the front.  man did that make a huge difference in vibration, and in having the knob not rotate.

Here is my BM26 running full out, passing the nickel test.  I think any more vibration, and it would not have passed.  But, having that much moving mass, and squelching vibration to this degree, it's pretty impressive.  I did have to place the nickel towards the center of table. 

 

Maybe the issue I have with mine.. since on both of mine I run the lever toward the back.. both are smooth running except in a couple of different speed ranges.. I'm going to try that once I get back in the shop.. Thanks for sharing this.. Now that Scott has joined in on this message.. I might be selling the couple older Hawks I have for a new BM series.. depending on how all this pans out..

Kevin 

[rjweb]

 In the near future will see how this all works out, and we get Iggys review,  the good part is that Scott from Buston has joined in the conversation, RJ

[hotshot]

11 hours ago, tonylumps said:

Does anyone own a new BM 20 or 26 on SSV.that has been using it long enough for a review.According to Bushton they are really selling a lot of them. Is it mostly production type of work.I know we will get a good review from Iggy But is there anyone else using the new Models.

There have been a very very few buyers of the BM on the forums.  

Here is a thread from SSWC where FretFret explains the positives of the switch from the Dewalt to the BM, so this may be what you are looking for:  https://forum.scrollsawer.com/forum/scroll-saw/tools-and-blades/835039-hawk-scroll-saw

The BM20/BM26 series is in the same bloodline as the G4, so even though Rolf doesn't own this saw, he knows the G4 inside and out, and he has gotten a little time on a BM, so his perspective should be pretty good.  https://forum.scrollsawer.com/forum/scroll-saw/tools-and-blades/50224-new-hawk-20-inch-saw

On this forum, FlyingPigs/Doug explains why he gave up on the BM after struggling for < 10 hours. (BM220). (He went on to buy a Seyco and seems very pleased)

So Doug was breaking a lot of blades and struggling with Spirals.  I think I agree with Doug on the Clamp Knobs but for a different reason.  I do believe the rotating head is a much better design, but not only to prevent the Hockey Stick effect, but because "I believe" the rotating head allowed the clamp to be tighter with the same amount of effort.  I have had the blades come loose on the BM multiple times, and this was with knobs shipped fresh from Bushton.  I can crank down on them, and not have that issue, but it requires less effort to get the clamps to that same holding tension on the Ex, DW788, and Hegner, which all use the rotating clamp knob end.  I have had the hockey stick effect on the BM with the smaller blades, so that may have been why Doug was breaking blades.  I am concerned that I will not be able to do my coins with the BM, as Jewelers blades requires a lot less tension, and my playing around so far has me doubting, but we shall see.

Since Scott Smith has indicated that I may eventually be able to get untapped clamps, that may become a non-issue with me, and bring this saw over the top for me.  What would be even better is if they were willing to tap the clamp for my desired thread size for me, but beggars can't be choosers.  If this does happen, you will see a delightful post at some point in the future.  It may be long long time until they make their clamp production runs, so I may have a long wait.

Bonus Trivia:  Nilus has his doctorate in Mechanical Engineering (according to a reliable source).  I think the improvements to the Hawk saws show that he has some talent to go along with the degree.  That problem solving mentality is good and I hope that effort to improve the saw continues going forward.

Edited July 23, 2017 by hotshot

[hotshot]

I have a question for any machinist (or folks that know this kind of thing).  I'm pretty sure what I have in mind will work, but I wanted to sanity check my assumptions.

The current BM clamps are drilled somewhat less than 1/4" (13/64") and tapped at 20 threads per inch to result in it accepting a 1/4" X 20 Thumbscrew.

The knobs I want to use are M6 and tapped to 1 thread  per mm.  In inches, the outer diameter of the shaft would be 0.23622 which is really really close to 1/4"

So the question is, if Bushton sends me untapped clamps drilled at 13/64", am I going to be able to tap them using the M6 X 1 tap?  The normal hole size for that tap is 5 mm or 0.197". 

So Bushton Hole is 0.203125"  vs M6 hole which would be 0.19685" for a difference of .006275", so we can say the hole is about 6 thousands too big which seems like it would be close enough, am I right?

I'm not a machinist, so my Math could totally be screwed up, but I know the M6 thumbscrews are close to the same size as the 1/4" because the M6 X 1 starts to thread into the Bushton clamp.  At the end of the day, if I can get this to happen, I will have a Hawk Clamp that will take a Thumbscrew from the DW/EX/Seyco/Hegner and make use of that rotating tip.  I really think that would help.

Edited July 23, 2017 by hotshot

[tonylumps]

13 hours ago, hotshot said:

There have been a very very few buyers of the BM on the forums.  

Here is a thread from SSWC where FretFret explains the positives of the switch from the Dewalt to the BM, so this may be what you are looking for:  https://forum.scrollsawer.com/forum/scroll-saw/tools-and-blades/835039-hawk-scroll-saw

The BM20/BM26 series is in the same bloodline as the G4, so even though Rolf doesn't own this saw, he knows the G4 inside and out, and he has gotten a little time on a BM, so his perspective should be pretty good.  https://forum.scrollsawer.com/forum/scroll-saw/tools-and-blades/50224-new-hawk-20-inch-saw

On this forum, FlyingPigs/Doug explains why he gave up on the BM after struggling for < 10 hours. (BM220). (He went on to buy a Seyco and seems very pleased)

So Doug was breaking a lot of blades and struggling with Spirals.  I think I agree with Doug on the Clamp Knobs but for a different reason.  I do believe the rotating head is a much better design, but not only to prevent the Hockey Stick effect, but because "I believe" the rotating head allowed the clamp to be tighter with the same amount of effort.  I have had the blades come loose on the BM multiple times, and this was with knobs shipped fresh from Bushton.  I can crank down on them, and not have that issue, but it requires less effort to get the clamps to that same holding tension on the Ex, DW788, and Hegner, which all use the rotating clamp knob end.  I have had the hockey stick effect on the BM with the smaller blades, so that may have been why Doug was breaking blades.  I am concerned that I will not be able to do my coins with the BM, as Jewelers blades requires a lot less tension, and my playing around so far has me doubting, but we shall see.

Since Scott Smith has indicated that I may eventually be able to get untapped clamps, that may become a non-issue with me, and bring this saw over the top for me.  What would be even better is if they were willing to tap the clamp for my desired thread size for me, but beggars can't be choosers.  If this does happen, you will see a delightful post at some point in the future.  It may be long long time until they make their clamp production runs, so I may have a long wait.

Bonus Trivia:  Nilus has his doctorate in Mechanical Engineering (according to a reliable source).  I think the improvements to the Hawk saws show that he has some talent to go along with the degree.  That problem solving mentality is good and I hope that effort to improve the saw continues going forward.

So Iggy will be the first to test ride the new Bushton made Saw here on SSV.Iggy the pressure is on

[Gonzo]

9 hours ago, hotshot said:

I have a question for any machinist (or folks that know this kind of thing).  I'm pretty sure what I have in mind will work, but I wanted to sanity check my assumptions.

The current BM clamps are drilled somewhat less than 1/4" (13/64") and tapped at 20 threads per inch to result in it accepting a 1/4" X 20 Thumbscrew.

The knobs I want to use are M6 and tapped to 1 thread  per mm.  In inches, the outer diameter of the shaft would be 0.23622 which is really really close to 1/4"

So the question is, if Bushton sends me untapped clamps drilled at 13/64", am I going to be able to tap them using the M6 X 1 tap?  The normal hole size for that tap is 5 mm or 0.197". 

So Bushton Hole is 0.203125"  vs M6 hole which would be 0.19685" for a difference of .006275", so we can say the hole is about 6 thousands too big which seems like it would be close enough, am I right?

I'm not a machinist, so my Math could totally be screwed up, but I know the M6 thumbscrews are close to the same size as the 1/4" because the M6 X 1 starts to thread into the Bushton clamp.  At the end of the day, if I can get this to happen, I will have a Hawk Clamp that will take a Thumbscrew from the DW/EX/Seyco/Hegner and make use of that rotating tip.  I really think that would help.

Yes, you should be fine. (20 plus years as a machinist)

[Iguanadon]

1 hour ago, tonylumps said:

So Iggy will be the first to test ride the new Bushton made Saw here on SSV.Iggy the pressure is on

The pressure is on, and I'm a one trick pony in that I only cut 1 type of thing in 3/4" poplar and pine... Not gonna be a lot of in-depth information to gather from what I have to say I'm afraid but I look forward to sharing whatever I can that may help others.

[tonylumps]

1 hour ago, Iguanadon said:

The pressure is on, and I'm a one trick pony in that I only cut 1 type of thing in 3/4" poplar and pine... Not gonna be a lot of in-depth information to gather from what I have to say I'm afraid but I look forward to sharing whatever I can that may help others.

Iggy you are cutting a lot of 3/4".That is a fairly good test You are cutting Puzzles If the Keyes slide out  both ways Thats a good test.If you were cutting some 1/8 that would help .But some one else will have to jump in on that.Ease of use is a big concern (blade changes) along with Vibration I am sure the saw was built to last.

[Rolf]

First I want to thank Scott and Bushton for jumping on getting this issue resolved. I wish I lived closer if they let me I would volunteer with final QA.  

Tap drill size is also dependent on material to be taped. You don't want a sloppy thread in aluminum. 

This chart gives some good information.

https://littlemachineshop.com/reference/TapDrillSizes.pdf

The comment about the rear cam lever facing forward or back is interesting. I run my G4 with it facing towards the back because the outer castings come up higher so with the cam lever facing forward the lever would on occasion move a bit and tap against the frame. So I would get this light ticking that drove me nuts . But I will swing it back forward and do a vibration test, not that I have much.

On another note After 12 years of hard labor I replaced a part on my saw. The original pitman arm (plastic) has what looks like a carbon or graphite bushing at the top and a ball bearing where it attaches to the motor. I have never lubed it  at the bushing. I bought a new one at one of the open houses and  it has an Oillite bronze bushing. The old one had just a few thousandths of an inch play, The difference is amazing.  

GONZO Finding machinists and Tool makers is getting to be very difficult in our area. I managed a small  experimental machine shop for ~20 years. My dad was an old world German tool maker and he passed on a few skills.  The skills are not taught anywhere and no apprentice programs exist. When the current staff retires it will be a real problem.

 

[kmmcrafts]

I did go out this morning and run the tension adjuster at the back of the saw toward the front.. It's amazing how that effects the saws vibration and noise level.. Purs like a kitten now.. and the awful noise and vibration at top speed is almost completely gone.. pretty sure it would pass the nickle test now..

 

Kevin  

[Mark1]

Hi Hotshot,

The tap drill size runs about 80%.  This is pretty much a standard in the metal working industry.  The example here is 80% of a .250 hole is .200.  All my life I've used a #7 number drill, (.201) as the tap drill size for 1/4-20 thread.  This 20% thread gives adequate strength without the tap breakage.  I have used larger tap drills in exotic material for the sole purpose of not breaking taps.  I can't ever remember drilling smaller tap drill sizes, although I probably have.

Metric is no different.  Just figure 80% of the major diameter.  If you ever measure the screw that threads into this tapped hole, you'll see that it is smaller than 1/4 inch.  This is to eliminate the need for the tap to cut dead sharp corners.

Don't overthink this, just use 80%.  If you feel the need to close up the clearance, you'll need to measure over thread wires and start working with pitch diameter.  I don't know how you would adjust this since the tap will cut the pitch diameter it is, and the screw is what it is.  The way this is done in industry is by grinding the threads of the screw that fits in.  This is coupled with custom ground taps.   If you want to see what ground threads look like, take apart a micrometer and look at the threads on the spindle.

I hope this helps you out.

Mark

PS  An M6 thread would be (theoretical) .236.  You should be drilling about .190, or so.  A .203 tap drill would only yield 14% thread.  IMO, that's a little thin.  From what you've posted, that doesn't sound like the direction you want to go.

 

 

Edited July 23, 2017 by Mark1

[JOE_M]

3 hours ago, Mark1 said:

An M6 thread would be (theoretical) .236.

I'm not a machinist but I've got all the tools (until Tuesday when someone comes for the lathe and surface grinder) and tapped quite a few holes (I also use a #7 for 1/4-20). If we go by real tolerances, an M6 major diameter is 5.974 max, 5.794 min. If I haven't messed up the math, that equates to .235" and a .188" hole, making a .203 even looser - and that's if you get the fattest M6 bolt sitting in the hardware drawer. That would make me agree with Mark1 that maybe this isn't the way you want to go.

Perhaps you could verify that they're making a 13/64 hole, and not a #7 hole, and once you know for sure just try it yourself on a scrap piece of metal. You can buy either one of those drill bits for less than $4 at your local hardware store. Drill the hole, tap it with your M6x1 tap, and see if you're happy with the fit.

 

 

 

[hotshot]

1 hour ago, JOE_M said:

Perhaps you could verify that they're making a 13/64 hole, and not a #7 hole, 

I'm so far outside my comfort zone I can't even see land.

I was assuming 13/64 based on some chart, but maybe they are just using the #7.  Only thing I know for sure is that their thumbscrew is 1/4 x 20, but the one I would like to use is a M6 x 1.  

Im hoping not to have to go the Heliocoil or time-sert route, if that would even work in this situation.

So, if I'm understanding right, in soft metals they usually drill with a #7 for 1/4 x 20 or a #8 for M6 x 1

So #7 is .201" and #8 is .199", so the hole will be .002" too large, which will mean the threads on the Thumbscrew will reach all the way outside of the threaded hole, but I will have slop closer to the shaft because the hole is too big.  I wonder how much slop we are talking about.  I might have to take Marks suggestion and test a m6 x 1 tap on #7 hole.

The other possibility is to ask for the clamps undrilled, if they are willing to do that, then just drill and tap myself.

Best solution would be if Bushton would offer these drilled and tapped for the M6 x 1.

Edited July 23, 2017 by hotshot

[stoney]

3 hours ago, hotshot said:

 

 

Best solution would be if Bushton would offer these drilled and tapped for the M6 x 1.

If I understand the issue with Hawk blade clamps it appears to best solution would be for Bushton to start using a rotating tip thumb screw in their clamps. JMHO   Please correct me if I am wrong.

[kmmcrafts]

1 hour ago, stoney said:

If I understand the issue with Hawk blade clamps it appears to best solution would be for Bushton to start using a rotating tip thumb screw in their clamps. JMHO   Please correct me if I am wrong.

That's what I was going to say.. I even went so far as trying to use my Dewalt screw in the Hawk clamp last year.. but as mentioned they are a different size.. I never put much more thought into it.. but yes.. best solution would be for Hawk to consider making their own style of thumb screw or change the size of the hole and buy those style that DeWalt or Excalibur use..

[DME72]

i  get the bent blades with my bm20 saw. only on the 2/0 blades though. i tried to lighten how hard i twist the blade clamps and the blade pulled out. i have only been using this saw about a month or so. in my experience the bm20 saw seems better to cut thick wood like puzzles and boxes and stuff with a bigger blade. i have tried to do some fretwork earrings with 2/0 blades and get the bent blade effect. has anybody else had the bent blade trouble?

 

doug

[hotshot]

3 hours ago, stoney said:

If I understand the issue with Hawk blade clamps it appears to best solution would be for Bushton to start using a rotating tip thumb screw in their clamps. JMHO   Please correct me if I am wrong.

I suspect manufacturing those would be very difficult, and keeping with "American Made" might make sourcing those difficult.  Well I thought "I know Bushton is not making the motors, and I seriously doubt those are American made . . .",  so, I got on my back under the saw to see who made the motor, and . . . Yes, it is American made by "Bison Gear and Engineering Corp."  Wow and Kudos to Bushton on keeping the "Made in America" message squeaky clean.  So given the no chinks in the armor, I don't think they would use the overseas sourcing.

Some time back, I did some extensive research, called "many" manufacturers, looking for the knurled knobs with the rotating ends (like Hegner but intended to use on EX), and many did have "Swivel Heads", but that is not the same thing, and will not for for our application.

But to your point, if Bushton gave us the option of  M6 x 1 and shipped without the knob, then we could easily handle the sourcing for ourselves and have the best of both worlds.

Edited July 24, 2017 by hotshot

[tonylumps]

About a year ago I was experimenting with my Hegner thump clamp Well to make a long story short I did drill a socket head screw out to except a rotating head from another thumb clamp.3 things you will need .A drill bit to fit the stem on the button .A centering bit to get the drill bit started .And a drill press would be a lot better than hand held

Edited July 24, 2017 by tonylumps

[stevan]

On ‎7‎/‎22‎/‎2017 at 0:25 AM, hotshot said:

I did find out what I was doing wrong, and it was "simple".  I had the rear tension lever engaged, but for some reason, I was thinking the end of the knob would face the back, not the front.  man did that make a huge difference in vibration, and in having the knob not rotate.

Here is my BM26 running full out, passing the nickel test.  I think any more vibration, and it would not have passed.  But, having that much moving mass, and squelching vibration to this degree, it's pretty impressive.  I did have to place the nickel towards the center of table. 

 

So I tried this on my 25 (+/-) year old Hawk and almost passed the test.  With the saw at full speed the nickel would stand upright for about 2 seconds and then fall over.  At the "harmonic" speeds, there was no way the nickel could stand up though.  Oh and I had the rear tension lever turned toward the front.

[Mark1]

Hi Hotshot,

I'll try to go over this again, being more specific.

Major diameter on the M6 screw is .236.  I looked up what is the recommended tap drill size, and it's 5MM (.200).  I initially told you about .190, which would be a #11 drill (.191).  In retrospect that may be a little tight, although it is 80%.  (FYI, a number 10 drill is .1935, #8=.199, #7=.201, and 13/64=.203)  In industry, if you don't have a 5M drill, a number 8 is recommended.

If Bushton supplies the holders drilled 13/64 (.203) that's kinda big.  I don't know where the 13/64 came from, my guess would be they're drilling it with a #7 drill (.201).  Just to spin your head in a complete circle, a drill will usually cut oversize.  If you use a .201 drill, you'll probably get .202-.203 if it's sharpened correctly.

I'm wondering if you may be taking the long way around the park on this.  I went to Amazon, (not my favorite place) and they sell 1/4-20 thumbscrews priced 20 for 10 bucks.  In my minds eye, I see you wanting to standardize your saws so all use the same thumbscrew on the blade holder?  Maybe it's past the point of diminishing return to do this.  (What do I know?)

I don't want this to sound condescending, I am trying to be helpful.  In my career, I've taught quite a few apprentices and the toughest ones to teach were the ones that wouldn't ask questions.  If what I'm writing doesn't make sense, you have to say something.  One tough aspect of teaching is to me, everything I say makes perfect sense.  It's been known to leave people scratching their heads more than once.

Mark

 

[Rolf]

Like Mark said the closest drill bit for an M6-1 in aluminum is a #8 drill. If you look at the chart that I linked to in my last post.

 

Regarding the rear lever and vibration. I have an App on my phone that measures vibration. On my G4 there is no noticeable difference between lever turned to the back or front.

I have a Samsung 6 and the app is Vibrometer. There are lots of apps for this, they put a a number to what you feel for comparison.

Edited July 24, 2017 by Rolf