Refit of Delta 14" Single Speed Woodworking Bandsaw to Three Phase Metal Cuttin

**rob streeper** · 18th January 2014, 09:12 AM

Having recently accomplished the mysteries of backsaw manufacturing I found myself in need of a method for cleanly cutting various types of metal including brass, bronze, mild-steel and 304 stainless steel. To this end I installed a 93.5" X 0.5" Lenox Trimaster blade in my 14" Delta bandsaw. On wood and brass it worked great - I could feed material as fast as I felt like pushing it across the table. Sawing stainless steel handsaw backs made by folding 0.083" 304 SS proved to be a different matter entirely. I noticed at first that the cut edges were coming out rough. On examination I found the blade had begun to lose some carbide tips. Checking the Lenox website I found that the blade speed recommendation for this job was ~ 80 feet-per-minute. Measurement of the motor and drive pulleys of the saw revealed diameters of 2 1/4" and 4 9/16". These combined with the drive wheel diameter of 14" and a motor speed of 1750 R.P.M. produced a blade speed of 3165 F.P.M., obviously way too fast.

To obtain the required 80 F.P.M. I obviously needed to do some modifications. First the calculations.

80 F.P.M X 12 in./ft. = 960 I.P.M maximum blade speed

14" saw wheel diameter X 3.14 = 43.96" drive wheel circumference.

960 I.P.M. / 43.96" = 21.8 R.P.M.

1750 R.P.M motor speed / 21.8 R.P.M. = 80:1 reduction in shaft speed required. Obviously I could not fit up belt pulleys with circumferences of 1" for the drive and 80" for the driven pulleys.

Thus what to do?

The answer is installation of a combination of a reduction jack-shaft and a 1 h.p. three phase motor running on an adjustable variable frequency drive.

The Teco JNEV-101-H1 converts 120V single phase AC to 240V 3 phase and allows continuous variation of the output from 100% down to 20%. Thus the drive will allow a nominal 1725 R.P.M. motor to operate at 1725 R.P.M. X 0.2 = 345 R.P.M.

345 R.P.M. motor / 21.8 R.P.M required = 15.82:1 final drive ratio - much more manageable.

A survey of the chassis of the Delta saw revealed that it would easily accommodate a 10" primary drive pulley. Running this off of the output of a 1.75" jack-shaft pulley gives a reduction ratio of 5.7:1. The jack-shaft 4" driven pulley running off of a motor pulley of 1.5" gives another reduction ratio of 2.67. for a combined ratio of 2.67 X 5.7 = 15.2:1. Thus the final drive speed is (1725 X 0.2) / 15.2 = 22.69 R.P.M. for a blade speed of (22.69 R.P.M. X 43.96" / revolution) / 12 = 83.1 F.P.M. I say close enough.

Some searching on-line yielded the following treasures. 0.75" pillow blocks and stops (2 ea.), 0.75" X 12" slotted shafting, 3/16" key stock, 2"-4"stepped jack-shaft pulley, Power Twist Plus Link V-belt, Teco VFD, Baldor 3-phase 1 hp 1725 R.P.M. motor, 10" drive pulley and 1.75" motor pulley.

The motor has yet to arrive so I thought I would get ahead of the work by installing the various pulleys and jack-shaft today. Here is the step-by-step.

First, find the bandsaw. Like many home craftsman space is a problem.

where is that bandsaw 2.jpg

Next, lay out all of the parts.

pieces to be assembled today.jpg

Excavate the bandsaw and lay it down for wheel installation.

fit locking casters.jpg

Back upright and remove the stock drive pulley.

remove the old primary drive pulley.jpg

Clean up the new drive pulley key-way and fit the original key.

deburr the drive pulley key way.jpg

A quick look to make sure everything will fit.

Attachment 301128

Dry fit the jack shaft parts and mark mounting bolt holes.

test fit the jack shaft to locate mounting bolt holes.jpg

Mark the jack-shaft for cutting.

mark the shaft for shortening.jpg

Cut the jack-shaft.

shorten the shaft.jpg

Cut the jack-shaft key.

cut the jack shaft key.jpg

Fit the jack-shaft key to the shaft and pulley.

fit up the jack shaft pulley.jpg

Dress the cut end of the jack-shaft.

dress the cut end of the jackshaft.jpg

Drill pilot holes for mounting bolts.

boring pilot holes.jpg

Open out the mounting bolt holes.

open out the pilot holes.jpg

Assemble all jack shaft parts and mount to saw base.

jack shaft assembly completed.jpg

Attach the drive pulley, adjust the relative positions of the drive pulley and the jack-shaft pulley, install belts.

adjust belt alignment.jpg

And the drive speed reduction assembly is done. Looks dangerous no? I think I'll leave it exposed as a test of Darwinian fitness.

mechanical assembly done 2.jpg

Just now the doorbell rang and the motor has arrived.

and the motor just arrived.jpg

Part two will include the assembly of the electrical circuit and mounting the motor and VFD.

**rob streeper** · 20th January 2014, 12:30 AM

This is a relatively simple process. Unfortunately the box I bought to house the VFD is too small so I will cover that in a third post here.

First, here are the parts. Flexible plastic conduit, 14 ga. copper wire, conduit fittings, VFD, motor with pulley and key and crimp on connectors, zip ties and some self tapping screws.

materials for motor change.jpg

First remove the old motor.

remove the old motor 2.jpg

Remove the power line from the old motor and crimp on new spade clips to connect to the VFD.

spade clips on mains feed.jpg

Connect the refitted mains feed pigtail and mount the VFD to the upper wheel shroud using self tapping screws.

temporary mounting for VFD 2.jpg

Now for the new motor, first examine the motor data plate to determine the proper ordering of connections for the various coils.

wiring diagram 2.jpg

Identify the required coil leads, bundle them together and attach feeders to each bundle (3). Frotunately on this motor the coil leads are individually numbered making this job easy.

connect coil leads properly.jpg

Connect a ground lead to the motor frame. Mark the the feed end of the ground feed to identify it by snipping away a little insulation. Thread all of the leads through the junction box outlet and conduit adapter.

motor wiring done 2.jpg

Install the new motor.

attach motor to frame.jpg

Route the conduit up through the existing passages in the machine frame and connect the motor feeders to the VFD. Start with the ground. Use zip tie to temporarily secure the conduit pending acquisition of a box to house the VFD.

connect the ground first 2.jpg

Now connect the three phases to each of the terminals marked T1-T3.

Electrics connected 2.jpg

Now power on.

Power up 2.jpg

No sparks and the VFD fan turns on as expected. Now to check the motor rotation. One nice thing about three phase motors is that by switching the positions of any two of the T1-T3 leads you can change the direction of rotation. When I kicked the VFD on for the first time the motor was running the wrong direction. I simply swapped leads 1 and 2 and the motor did what I needed it to do.

Unfortunately I can't get the upload facility to accept my video of the saw in operation.

Now I need to obtain and fit a cover to protect the VFD and program the VFD for operation. I'll post a picture of the completed work here later.

**BobL** · 20th January 2014, 01:50 AM

Interesting project Rob.

I'm just wondering about the location of the VFD in relation to the cutting position.
Are you planning remote switching and speed control of some sort?
I reckon it would be useful to be able to adjust the speed while actually cutting especially is variable thicknesses on the same piece are involved.

Originally Posted by rob streeper

Unfortunately I can't get the upload facility to accept my video of the saw in operation.

If you can't get it to work try uploading to something like youtube and linking from there.

I'm also curious about why you have gone for an upright (as opposed to a horizontal) type of band saw for metal.

**rob streeper** · 20th January 2014, 01:57 PM

Originally Posted by BobL

Interesting project Rob.

I'm just wondering about the location of the VFD in relation to the cutting position.
Are you planning remote switching and speed control of some sort?
I reckon it would be useful to be able to adjust the speed while actually cutting especially is variable thicknesses on the same piece are involved.

If you can't get it to work try uploading to something like youtube and linking from there.

I'm also curious about why you have gone for an upright (as opposed to a horizontal) type of band saw for metal.

Hi Bob,

My main reason for modifying this saw is that I have no room for a horizontal saw. Also, I am using this to make backsaw backs from 304 stainless. Cutting the stainless requires a relatively slow blade speed. I will be cutting the SS lengthwise as the forming process often leaves unmatched faces so this mod allows me to trim them easily.
I am going to fit the VFD up to run off of the front panel rheostat and the whole assembly will ultimately be mounted such that it faces me while I operate the saw. I spent the majority of my working day today looking for an appropriate enclosure. I later ordered some parts off of Ebay so my next update will probably be in a week or so.

Thanks,
Rob

**BobL** · 20th January 2014, 02:48 PM

Originally Posted by rob streeper

Hi Bob,
My main reason for modifying this saw is that I have no room for a horizontal saw. Also, I am using this to make backsaw backs from 304 stainless. Cutting the stainless requires a relatively slow blade speed. I will be cutting the SS lengthwise as the forming process often leaves unmatched faces so this mod allows me to trim them easily.

It sounds like you are using it to rip folded plate so it makes sense to have an upright saw.

I am going to fit the VFD up to run off of the front panel rheostat and the whole assembly will ultimately be mounted such that it faces me while I operate the saw.

So will you be moving the VFD to the other side of the BS and if so how will you cope with the need to be able to easily open the blade cover door?

I spent the majority of my working day today looking for an appropriate enclosure. I later ordered some parts off of Ebay so my next update will probably be in a week or so.

I have my MW lathe VFD in an enclosure made from an old power tool box but the VFDs on my WW lathe and DP are only covered at the top by a piece of sheet metal to stop any dust fall out direct into the VSD.
So far dust doesn't seem to be a problem but I guess time will tell.

**rob streeper** · 20th January 2014, 03:14 PM

Originally Posted by BobL

It sounds like you are using it to rip folded plate so it makes sense to have an upright saw.

So will you be moving the VFD to the other side of the BS and if so how will you cope with the need to be able to easily open the blade cover door?

I have my MW lathe VFD in an enclosure made from an old power tool box but the VFDs on my WW lathe and DP are only covered at the top by a piece of sheet metal to stop any dust fall out direct into the VSD.
So far dust doesn't seem to be a problem but I guess time will tell.

I'm going to make my enclosure from an ammo can ripped on the long diagonal. I also plan to upgrade my Minimax 45 with a 3hp 3 phase motor in the near future.

**davidf** · 7th February 2014, 03:36 PM

Anyone know what the thread is on the holes in the front edge of the cast iron table of my Tauco bandsaw from the 1940's. From other forums I believe the Tauco is a re-branded American Delta brand for the Australasian market.
It is not 1/4 20 whitworth for example.
But about 1/4 inch and probably a finer thread.

I am thinking of fitting a fence to this bandsaw and hence want to use these threaded holes.

thanks in advance davidf

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