Thread: Titan Bandsaw !

Hi Guys,

No doubt some of you will remember this thread from some time ago ! And my attempts to get reasonably accurate measurements of the blade speed.

//metalworkforums.com/f65/t2014...ighlight=Titan

Well here I am some months on and deciding to try and reduce the blade speed. I had thought that if I could increase the size of the gear on the hub of the bottom driven wheel I could reduce the speed to within the range needed for cutting mild steel plate. Well I am only partially successful !

I found that the biggest toothed pulley that I could fit was 90 mm diameter, restricted by a tapered steel reinforcing rib behind the bottom wheel. Ringed in red in the picture.

a28-01-2018-003.jpg

So having decided on the largest toothed pulley that I could fit, I next had to work out what size belt I needed in order to drive it.
I ended up calculating that I would need a 150XLO37 belt. 10 mm wide with a 5.08 mm tooth spacing. So I bought both items. The pulley was an aluminium one made by Dunlop, of all people ! I thought they only made tyres, apparently not. They make a very wide range of toothed aluminium pulleys and drive belts. Anyway these are the two items that I bought.

25-10-2018-001.JPG 25-10-2018-002.JPG 25-10-2018-003.jpg

As can be seen the pulley needs machining to suit the existing bottom wheel on the bandsaw. Machining the pulley created some interesting machining problems. My Myford lathe only has a four inch three jaw chuck ! I could have used the six inch four jaw independent one but it would have been a little more awkward since the new pulley had a 15 mm tooth width and an overall thickness of 1" inch
(25 mm). I would have needed jaw protection and various packings, which after playing about with, I wasn't happy. Too many bits !

Quite some time ago I had purchased a set of soft jaws for the Pratt Burnard four inch chuck and they had sat in the draw, unused.
Since I had them I decided to use them. But I didn't want to carve most of them away just to hold this pulley. I'd seen a video where a chap had drilled and tapped the jaws on his chuck to fit sacrificial blocks to hold the workpiece. So I thought, why not do the same.

27-10-2018-001.JPG
These are the soft jaws ! You can see where I've marked the centre of the jaws so that I know how much stick out I have got to account for.

27-10-2018-002.JPG 27-10-2018-004.JPG 27-10-2018-005.JPG 27-10-2018-006.JPG
I marked out the position for the 5 mm hole, 18 mm deep in one jaw using a vice stop, then drilled all three, and tapped them M6. Those screws are 15 mm long.

27-10-2018-007.JPG
I used a piece of 1" inch diameter aluminium bar, drilled 6 mm, and parted off three 15 mm thick pieces. The piece of yellow strapping tape was used because the bar was not truly round.

27-10-2018-012.JPG
This is a family picture of the components of my modification to the new soft jaws. From left to right.
The new jaw, the alloy piece, below that, the M6 Allen cap screw and washer. Then another alloy piece.

27-10-2018-014.JPG 27-10-2018-013.jpg
This is the finished set ready for use, with the alloy pieces fastened to the jaws with the M6 cap screws. I could have used countersunk head screws but too lazy to look for them.

Part two coming up !

Hi Guys,

Sorry about dashing off yesterday.
Continuing the modifications to my Titan vertical bandsaw.

Having got my new soft jaws modified and ready to use, I put a piece of 40 mm round bar in the space between the middle of the jaws and tightened the chuck jaws so that it gripped the bar, this was done so that tension could be put on the scroll prior to turning the inside edge to accommodate the 90 mm toothed wheel.

27-10-2018-015.JPG
You can see in this picture how the alloy pieces grip the toothed wheel without damage and centering it perfectly. You can also see the lathe tool at the bottom right that I used to machine the alloy pieces. I also left a small step at the back so that the pulley sat square and true.

27-10-2018-016.JPG
Now since the pulley was 15 mm thick across the teeth and I needed it to be 10 mm, I turned the outside edge down right to the centre boss. Again I used the same tool as I had used to machine the alloy pieces that grip the wheel.

27-10-2018-017.JPG
I also needed to reduce the hub boss hight to 7.5 mm, which I did by taking 1 mm deep facing cuts. I actually removed just over 7 mm of material thickness here. The original plastic pulley had a 32 mm diameter machined step in the face to fit over a 3 mm step machined on the main drive wheel. So whilst I was machining the boss down I also machined a 4 mm deep by 32 mm diameter recess in the hub.

27-10-2018-019.jpg 27-10-2018-018.jpg
In these pictures you can see the 32 mm diameter raised section with the ball race visible and the three holes that were used to retain the original plastic pulley. Those faced areas you can see around the holes are 0.5 mm proud of the surface.

The next job was to mark and drill the three holes in the new toothed wheel. I used M5 screws to secure it to the driving wheel. So a 4.2 mm drill and spotting through to mark the toothed wheel ready for drilling and threading M5.

27-10-2018-021.JPG 27-10-2018-022.JPG 27-10-2018-023.JPG
Here the new toothed wheel has been drilled and threaded, then test fitted to make sure it all fits.

It was a good job that I spotted the holes onto the toothed wheel ! I soon discovered that one of the three holes was a millimetre off, outside the PCD. Meaning if I had just taken a measurement and drilled based on that, one of the holes would have been out of line.

I also didn't have three cheese head screws of the same length, so I had to cut two of them down to suit. Actually I ended up trimming them all down another couple of mm, so that they didn't stick proud of the toothed wheel surface.

It was now that I found that the alloy of the driven wheel was thin enough to flex as I tightened the screws, making it likely that the alloy of the wheel could fracture and distort causing the toothed wheel not to run true.

01-11-2018-002.jpg 01-11-2018-003.jpg
Well I had a short length of black PVC hollow bar 60 mm diameter by 12 mm wall thickness. So I cut a slice off with the chop saw, about 10 mm thick and used the soft jaws to grip it whilst I faced it down to 7 mm thick and bored it out to fit over the hub of the toothed wheel.

I actually had to take another 0.5 mm off the toothed wheel hub, reducing it to 7 mm. This was because I hadn't accounted for a 0.5 mm raised patch around the screw holes in the driven pulley.

01-11-2018-004.jpg 01-11-2018-005.JPG
Yes it fits, and I did remember to chamfer the inside edge to account for the radius in the root of the hub. All I needed now was to spot the holes through to clear the M5 screws.

01-11-2018-006.jpg 01-11-2018-009.JPG 01-11-2018-007.JPG
Notice that I had to mark the positions of the plastic ring and both the pulleys to make sure that I got them back in the same place each time.

01-11-2018-010.jpg
And now for a test fitting. Everything fits ! No ! not quite.
The shaft that the driving pulley sits on has a step right at the back, where the shaft diameter jumps up to 13.5 mm diameter.
Well I hadn't drilled out the toothed pulley bore since it was 1/2" diameter and cleared the bit of shaft where the bearings were.

Take it all apart and back into the lathe to open up the bore to clear the back of the spindle.
I didn't take any pictures of boring out the toothed wheel hub. I only bored out enough to clear the major diameter which was about 8 mm.

Suffice to say it all fits together nicely and the bandsaw runs well.

I'm stopping here and will do another bit later.

Hi Guys,

This is the last part of my notes about the Titan bandsaw.

After doing the modification of replacing the existing toothed wheel with a new larger one, the whole Idea being to reduce the linear blade speed to something more suitable for cutting steel than wood.

Several things became apparent. The biggest toothed wheel that I could fit was limited by the tapered web behind the driven wheel, and 90 mm was the only size I could fit without doing surgery to the tapered web. I ended up with only a couple of millimetres clearance. In addition the nearest toothed belt size I could get was a 150XLO37. Whilst there are belts listed above and below this size, non were available.

The pulley on the motor spindle is 25.5 mm in diameter and whilst I could get a 15 mm diameter pulley, the next nearest belt that I could get was a 160XLO37, which would be three or four teeth too big.

Anyway measuring motor spindle speed gave me 1460 rpm coupled with the 90 mm toothed wheel allowed me to measure 427 rpm on the driven wheel. This translates, assuming my maths is right, to 1050 surface feet per minute. A speed reduction of about four from what it was previously.

So whilst I have achieved a reduction in speed it is still in the region of four or five times too fast.

I'm not inclined to start cutting that tapered web down to fit a still larger toothed wheel at the moment. I estimate that I would need to use a 200 mm diameter toothed wheel to get the speed down into an acceptable range, bearing in mind that the driven wheel diameter is 240 mm. However it shows that it could be done.

Thank you all for your support and patience reading this post.

Hi John,
I like your soft jaw set up, I am sure you will use it quite a few times in the future.Would it be possible to do a speed reduction on the motor outside of the band saw case.
Bob

I agree with Bob, most wood bandsaws I've seen modified for cutting steel etc have have either a gearbox or a further reduction using pulleys etc.

Originally Posted by BaronJ

...Anyway measuring motor spindle speed gave me 1460 rpm coupled with the 90 mm toothed wheel allowed me to measure 427 rpm on the driven wheel. This translates, assuming my maths is right, to 1050 surface feet per minute. A speed reduction of about four from what it was previously.

So whilst I have achieved a reduction in speed it is still in the region of four or five times too fast.

Maybe check that. From memory mild steel cutting speed is around 30m per minute, which is roughly 98 feet per minute. By that you are 10x too fast. Doesn't sound right - I'd go back and recalculate your surface speed as even if the bandsaw was designed for wood, it would be around 100m per minute (= 328ft per minute). From what you are saying, the bandsaw after your mods to reduce speed is still 3 times faster than it would need to be for cutting wood.

Michael

Originally Posted by Michael G

Maybe check that. From memory mild steel cutting speed is around 30m per minute, which is roughly 98 feet per minute. By that you are 10x too fast. Doesn't sound right - I'd go back and recalculate your surface speed as even if the bandsaw was designed for wood, it would be around 100m per minute (= 328ft per minute). From what you are saying, the bandsaw after your mods to reduce speed is still 3 times faster than it would need to be for cutting wood.

From https://www.sawblade.com/band-saw-bl...feed-chart.cfm, the recommended speeds for mild and free machining steels are between ~150 and ~300 fpm depending on thickness, 314/6 stainless is between 60 and 90, again depending on thickness. Of course you can always cut slowly at even slower speeds but not at higher speeds without causing blade damage.

Most wood bandsaws operate at 1500 to 3000 fpm although they can operate more efficiently at higher speeds.

Originally Posted by BaronJ

The pulley on the motor spindle is 25.5 mm in diameter and whilst I could get a 15 mm diameter pulley, the next nearest belt that I could get was a 160XLO37, which would be three or four teeth too big.

Hi John, my maths are terrible, but if you were to fit the 15mm pulley, what would the speed be then?
To help with the adjustment, could a roller bearing be used on top to take up the slack?
Also a shorter belt would be required, not a longer one?
Kryn

Originally Posted by krisfarm

Hi John,
I like your soft jaw set up, I am sure you will use it quite a few times in the future.Would it be possible to do a speed reduction on the motor outside of the band saw case.
Bob

Hi Bob,
I don't know ! I haven't investigated that possibility at all. The steel frame is only a couple of millimetres thick behind that wheel and there is a thick steel ring with four bolts through the side at 90 degrees, holding the bottom wheel shaft, and welded to the flat panel. I'll take a picture of it later and post it.

I did consider moving the bottom wheel further away from the panel, to give me a little more room to fit a bigger toothed wheel, but then it would move out of line with the motor pulley.

Originally Posted by Michael G

Maybe check that. From memory mild steel cutting speed is around 30m per minute, which is roughly 98 feet per minute. By that you are 10x too fast. Doesn't sound right - I'd go back and recalculate your surface speed as even if the bandsaw was designed for wood, it would be around 100m per minute (= 328ft per minute). From what you are saying, the bandsaw after your mods to reduce speed is still 3 times faster than it would need to be for cutting wood.

Michael

Hi Michael,
From the bandsaw speed tables I've seen, for a bi-metal blade, 300 SFM is suggested, and for a carbon steel blade around 200 SFM. Both figures for mild steels, with speeds dropping by a factor of 10 for stainless steels ! Even then these figures are given for material thickness’s of less than 25 mm.

It cuts brasses and aluminium's just fine as it is now. But unless my sums are wrong, and they usually are, it is still way too fast for steel.

If you Google wood bandsaw to metal reduction you will find hundreds that have done it before.
I remember posts on forums 10/15 years ago explaining it all but not needing it I just read all about it and moved on.
Here is something like I was suggesting from a quick Google search.

Originally Posted by BobL

From https://www.sawblade.com/band-saw-bl...feed-chart.cfm, the recommended speeds for mild and free machining steels are between ~150 and ~300 fpm depending on thickness, 314/6 stainless is between 60 and 90, again depending on thickness. Of course you can always cut slowly at even slower speeds but not at higher speeds without causing blade damage.

Most wood bandsaws operate at 1500 to 3000 fpm although they can operate more efficiently at higher speeds.

Hi Bob,

Thank you, that is one of the charts I seen and use as a reference, the other was an information sticker that was attached to the roll of blade I saw when the chap was making up the blade for me.

Originally Posted by KBs PensNmore

Hi John, my maths are terrible, but if you were to fit the 15mm pulley, what would the speed be then?
To help with the adjustment, could a roller bearing be used on top to take up the slack?
Also a shorter belt would be required, not a longer one?
Kryn

Hi Kryn,
Yes you are quite right ! Me getting confused as usual
Reducing the motor pulley size would not get me very much at all ! Plus the pulley on the motor is pressed onto splines and held with a small left hand screw in the end. I've also noticed that it has a very slight wobble.

Hi Guys,

The pictures I promised earlier of the way the bottom wheel spindle is held in place.

IMG_0038.jpg IMG_0041.jpg
As can be seen, it is a welded on ring with four bolts securing the 13.5 mm diameter shaft. The parts to the top left are the table tilt and locking mechanism. It would be quite difficult to modify to add an external pulley system.

Thanks for the comments ! All advice and suggestions are welcome.

What would need to be done is,
Remove the motor, make a shaft with bearing/supports etc and mount the motor pulley one end and a larger pulley the other.

Then either mount the motor under the bench/stand or towards the rear of the machine with a small pulley.